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Locomotive BASIC

2025-01-14T19:47:17Z

Esesci: add max variable length information

For other BASIC language versions see the [[:Category:BASIC]]

[[Image:Screenshots-CPC_Start_screen.jpg|thumb|CPC Start Screen showing Locomotive copyright and BASIC version]]

Locomotive BASIC was a [http://en.wikipedia.org/wiki/BASIC_programming_language BASIC] interpreter for the Amstrad CPC range of computers.

It was availlable directly from in-built ROMs on [[CPC old generation]] and on the [[Plus System Cartridge]] for the [[Plus]] range. [https://benchmarko.github.io/CPCBasic/ Online Interpreter]

== Description ==

Locomotive BASIC, was one of the best and fastest BASIC implementations of the era. The language benefited both from a clean, well-thought out implementation of the core language by Locomotive, and by the excellent [[firmware]] of the CPC, which lent most of its advanced features to the BASIC.

Unlike the competing [[Commodore 64]], it featured a comprehensive graphic capabilities with its PLOT, DRAW, PAPER, INK, PEN, BORDER and (in BASIC 1.1) FILL commands. It had extensive sound commands, granting control of the [[AY-3-8912]] via the firmware's volume and tone envelope system. With the SOUND command, you could select channels, set envelopes, pitch, noise and volume. That was something unmatched by other computers of that era.

Also there was simple interface for memory management, with MEMORY and LOAD commands. The latter allowed for loading of raw screen data, thus providing easy picture showing. Both through this (combined with CALL, PEEK and POKE) and the firmware's [[RSX]] system, it was easy to mix BASIC and assembly code, thereby speeding up programs by coding the slowest parts directly in machine code. Many successful programs, including games such as [[Radzone]] and applications such as [[PowerPage]], made use of this technique.

With DEF FN, ON variable GOTO and ON variable GOSUB, Locomotive BASIC provided the rudiments of "structured programming", though nowhere near the extent of the PROCedures of [[BBC Basic]].

All in all, if you compare BASIC interpreters of that era, the Locomotive's seems to be the best 'all-rounder' regarding the combination of speed and complexity, and still some of its features were unmatched by others.

If you are interested in more information about the different versions of the CPC's BASIC and the technical details, you can have a look at the article "[[Technical information about Locomotive BASIC]]".

Another helpful and further resource of information about BASIC and a similar comprehension to this is Grimware's Website about the CPC http://www.grimware.org/doku.php/documentations/software/locomotive.basic/start

== History ==

The CPC implementation of Locomotive BASIC was developed directly from [[Locomotive Software]]'s existing Z80 BASIC. The existence of this is cited as one of the reasons Locomotive requested that [[Amstrad]] change the CPC's processor from a 6502 to a [[Z80]].

The 464 and Spanish 472 shipped with BASIC 1.0 on ROM.

The language was revised and debugged for the 472 (British), 664, 6128 and Plus machines to become BASIC 1.1. Changes were minor but significant for the programmer, and included:

* DEC$ bug removed (in BASIC 1.0, it required two opening brackets and was undocumented)
* Better handling of string arguments to RSXs (|DIR,"*.BAS" rather than a$="*.BAS":|DIR,@a$)
* DATA statements can appear anywhere within a line; in BASIC 1.0, they had to be at the end of a line
* FILL command (fill area with solid colour)
* COPYCHR$ function (fetch character from screen)
* Better garbage collection
* Some number-handling bugs removed (e.g. in FOR loops with negative start/end values)
* FRAME (CALL &BD19)
* Extra, optional 'plotting mode' parameter for DRAW/PLOT commands (supported only through control codes on BASIC 1.0)
* GRAPHICS PAPER, GRAPHICS PEN commands
* ON BREAK CONT (disable ESCape)
* CLEAR INPUT (flush keyboard buffer)
* The AUTO command show the whole line if it exist, it only printed a * on the 464

Some parts of 'BASIC' were actually housed in the firmware ROM, but were not officially accessible to other programs. This included the line editor.

The 'pure BASIC' parts of Locomotive BASIC - i.e. those not concerned with CPC-specific firmware and hardware features - were upgraded to become [[Mallard BASIC]], the CP/M language shipped with the [[PCW]]. This also featured exceptionally advanced random-access file handling, a feature missing from the CPC.

== Variables ==
Many contemporary BASIC interpreters only supported the first few characters of a variable name as a discriminator. For example <code>WATER$</code> and <code>WALDO$</code> would refer to the same variable on a Commodore 64 or Apple II. But Locomotive BASIC allowed variable names up to 40 characters in length, so <code>THEQUICKBROWNFOXJUMPEDOVERTHELAZYDOGFAST$</code> and <code>THEQUICKBROWNFOXJUMPEDOVERTHELAZYDOGFATS$</code> could be use as separate variables.

=== Real (Floating Point) Numbers ===

This is the default type for a Locomotive BASIC variables, but can be clarified using <code>!</code> after the variable name, e.g., <code>real!=500.0</code>.
You can force all variables starting with specific letters to be this type by using the <code>DEFREAL</code> keyword.
In many cases you don't want to use these, as they are slower than using the integer type, and use more memory (5 bytes, as opposed to 2).

=== Signed 16-bit Integers ===

Defined using <code>%</code> after the variable name, e.g., <code>integer%=500</code>.
You can force all variables starting with specific letters to be this type by using the <code>DEFINT</code> keyword.
These can store values between -32,768 and 32,767.
To assign a 16-bit value to a signed integer directly, you should give the number in a hexadecimal format, e.g., <code>uint=&c0000</code>.

=== Strings ===

These are defined by using <code>$</code> after the variable name, e.g., <code>str$="Hello"</code>.
You can force all variables starting with specific letters to be this type by using the <code>DEFSTR</code> keyword.
A String can be up to 255 characters long.

== Type Conversions ==

The BASIC functions <code>ROUND</code>, <code>INT</code>, <code>CINT</code> and <code>FIX</code> can be used to convert real numbers into integers taking some care about rounding. The difference is in rounding mode - <code>ROUND</code> rounds to nearest, <code>FIX</code> rounds to zero, <code>INT</code> always rounds down, and <code>CINT</code>rounds up. e.g., <code>value%=INT(3.14)</code>. Note that if you don't specify the % you will actually get a real number still.

To convert an integer to a real number, you can use the <code>UNT</code> function which will take the value supplied and return the two's complement number. e.g., <code>real=UNT(&ABCD)</code>.

<pre>
w=UNT(50000)
Ready
PRINT w
-15536
Ready
█
</pre>

If you want an integer result from division, use the <code>\</code> integer division operator. e.g., <code>int=value\divisor</code>. This is as opposed to the standard <code>/</code> division operator, that can create a real number.

== Command list ==

=== Commands and operators ===

==== <code>AFTER ‹time delay›[,‹timer number›] GOSUB ‹line number› </code>====
: Waits for ‹time delay›/50 seconds and then jumps NON-RECURRING to the subroutine at ‹line number› (see also <code>"EVERY i[,t] GOSUB line"</code>).

==== <code>AUTO [‹line number›][,‹increment›] </code>====
: Automatically generates line numbers starting at ‹line number› with ‹increment› after each entered line number. Use '''[ESC]''' to leave AUTO mode. Default values for ‹line number› and ‹increment› are 10.

: Example:
<pre>AUTO 100,5 :REM generates line numbers 100, 105, 110...</pre>

==== <code>BORDER ‹colour›[,‹colour›] </code>====
: Changes the colour of the border. If the second argument is supplied the border flashes between the two colours.

==== <code>CALL ‹address expression›[,‹list of: parameter›] </code>====
: Allows a machine code routine to be called by BASIC. Variables, string values and constants can be passed to the routine. Values of any supported type can be passed back by supplying a variable with <code>@</code> in front of it. This passes the address of the variable to the routine although it doesn't implicitly know the data type.
: Example:
<pre>CALL 0 :REM resets the computer completely</pre>

==== <code>CAT</code> ====
: Displays the names of the files on the tape or disc. Tape files are displayed in the order they are encountered. Disc files are sorted alphabetically by ACSII code. Only files matching the current user are displayed. Files marked as system are not displayed.
: Examples:
<pre>CAT :REM lists all disc files in alpha-numeric (ASCII) order</pre>

<pre>|TAPE :CAT :REM lists names of all tape files in their storage order</pre>

==== <code>CHAIN ‹file name›[,‹line number expression›] </code>====

:Enables the specified program to be loaded and RUN automatically. If the optional parameter ‹line number expression› is specified, the program execution will commence from that line.

==== <code>CHAIN MERGE ‹file name›[,‹line number expression› | [,[‹line number expression›],DELETE ‹line number range›]] </code>====

:Loads the specified program from tape or disc, merges it into the program in memory, and starts execution of the merged program. The parameter <code>DELETE</code> ‹line number range› is used to delete part of the original program before running it, if required.

==== <code>CLEAR</code> ====
: Clears all variables from memory, leaving the program in memory unchanged. All open files are abandoned.
: The command clear inside a subroutine (<code>GOSUB</code>... <code>RETURN</code>) will also clear the "stack pointer" address of the gosub heap. That means that a RETURN won't work and a GOTO has to be used instead.

==== <code>CLG [‹masked ink›] </code>====
: Clears the graphics screen to colour specified by <code>‹masked ink›</code>. If parameter <code>‹masked ink›</code> is not specified then the graphics screen is cleared to the colour specified by the GRAPHICS PAPER statement.

==== <code>CLOSEIN</code> ====
: Closes any input file (tape or disc).

==== <code>CLOSEOUT</code> ====
: Closes any output file (tape or disc).

==== <code>CLS [#‹stream expression›]</code>====
: Clears the window specified by ‹stream expression›. If ‹stream expression› is omitted it defaults to #0 (usually the whole screen). The text cursor of the stream is moved to the upper left corner.

==== <code>CONT</code> ====
: CONTinues program execution interrupted either by [ESC] [ESC] or as a result of STOP within a program. A program cannot be continued after being modified.

==== <code>CURSOR ‹expression› </code>====
: <code>‹expression›</code> must be either 0 or 1.

==== <code>DATA x1[,x2,x3...]</code> ====
: Defines a data ''section'' to be used by <tt>READ</tt> calls.
: Data values can be of any type (integer, real or string) as long as the corresponding <tt>READ</tt> calls use a variable of the right type.

:Example:

<pre>
10 DATA "Hello, world!", 42
20 READ message$:PRINT message$
30 READ answer:PRINT "The answer is:";answer
</pre>

:''See also:'' <tt>READ</tt>, <tt>RESTORE</tt>

==== <code>DEF</code> ====
: DEF means "define" and comes along with defining a function in case of DEF FN or defining variables in case of DEFREAL, DEFINT or DEFSTR.
: DEF FN must come before using the statement FN.
: DEF with a variable declaration should come before using a variable.
: (see also FN)

==== <code>DEFINT ‹letter range›</code> ====
:Forces all variables(s) starting with the specified letter(s) to be integer variables. Singular letters could be defined or a range by a minus symbol between two letters.

:Examples:
<pre>
20 DEFINT a-z:' sets all variables starting with an A until Z as integer.
</pre>
or
<pre>
10 DEFINT F,S ..... (or 10 DEFINT A-Z)
20 FIRST=111.11:SECOND=22.2
30 PRINT FIRST,SECOND:' prints out 111 22
</pre>

==== <code>DEFREAL ‹letter range›</code> ====
: Sets the default for variable(s) with the specified first letter(s) to a floating point figure.

==== <code>DEFSTR ‹letter range›</code> ====

: Sets the default for variable(s) with the specified first letter(s) to string(s) variables.

==== <code>DEG</code> ====
: Switch to degrees mode for trigonometric functions (<tt>SIN</tt>, <tt>COS</tt>...).
: ''See also:'' <tt>RAD</tt>

==== <code>DELETE [first line][-[last line]]</code> ====
: Deletes the current program completely (without arguments) or only the given line or line range. Even
: <code>DELETE -</code>
: is legal, it has the same effect as
: <code>DELETE</code>
: The lines specified do not have to exist, all lines matching the range will be deleted and having no matches does not cause an error.

==== <code>DI</code> ====
: Disables interrupts (but not[ESC]) until re-enabled by EI command or by RETURN at end of an interrupts service routine.
: This means that DI (if it's activated in a subroutine) is useful helping a low-priority-interrupt not to be stopped by a higher-priority-interrupt. RETURN then re-enable the interrupt without EI.

==== <code>DIM a[%|!|$](d1[,d2[,...]])</code> ====

: Creates array <code>a</code> with single or multiple dimensions. You may optionally specify integer (<code>%</code>), real (<code>!</code>) or string (<code>$</code>) type otherwise it defaults to the current type set for the first letter of the array name. <code>d1</code> is size of first dimension-1, <code>d2</code> is size of second dimension-1 and so on. <code>DIM x(10)</code> will create an array with 11 elements, <code>x(0)</code> is the first element, <code>x(10)</code> is the eleventh and last. You can specify as many dimensions as will fit on one 255 character line, which is a maximum of 125. Trying to create an array that already exists will generate an <code>Array already dimensioned</code> error. If an array is not specified by <code>DIM</code> before being accessed, each dimension value defaults to 10. The maximum dimensions that can be created this way is three.

==== <code>DRAW x,y[,[i1][,i2]]</code> ====

: Draws a line from the current cursor position to position x,y. i1 specifies colour, i2 is the drawing style.

: 4 drawing styles:
<pre>
i2 = 0 normal colour
i2 = 1 XOR colour
i2 = 2 AND colour
i2 = 3 OR colour
</pre>
: Example:
<pre>
CLG 2
DRAW 500,400,0 :REM draws a line from 0,0 to 500,400
</pre>

<code>DRAWR xr,yr[,[i1][,i2]]</code> ====

: Draws a line from current graphics cursor position to current cursor x position + xr, current cursor y position + yr. i1 and i2 as DRAW.
:Example:

<pre>
Move 200,200
DRAWR 100,100,0 - draws a line from 200,200 to 300,300
</pre>

==== <code>EDIT ‹line›</code> ====
: Display 1 program line for editing.

The following keys can be used in editing mode, or during typing in BASIC:

CTRL+TAB - toggle overwrite/insert mode
CTRL+CURSOR LEFT or CTRL+CURSOR UP - go to start of line
CTRL+CURSOR RIGHT or CTRL+CURSOR DOWN - go to end of line
CURSOR LEFT - move left one character
CURSOR RIGHT - move right one character
ESC - quit editing and do not accept changes
ENTER/RETURN - quit editing and accept changes
SHIFT + CURSOR UP/DOWN/LEFT/RIGHT - enter copy mode. You can move the cursor to where you want to copy from. Hold SHIFT and cursors to move copy cursor.
COPY - copy character covered by copy cursor.
DEL - delete character and go back a char
CLR - delete character under cursor
CTRL + CAPS LOCK - toggle shift lock.

==== <code>EI</code> ====
: Enable interrupts which have been disabled by DI

==== <code>END</code> ====
: Indicates end of program

==== <code>ENT ‹tone envelope number›[,‹tone env. section›][,‹tone env. section›][,‹tone env. section›][,‹tone env. section›][,‹tone env. section›]</code> ====
:The ENT command define the TONE shape of a sound which means manipulating the frequency in a certain range.
:The command could looks like:
<pre>
ENT NUMBER,STEPS?,VERTICAL?,HORIZONTAL?
</pre>
:It is possible to define 15 different envelope shapes. So '''NUMBER''' could be 1-15.

:Each '''?''' stands for up to five sections (1-5), where each STEP<>VERTICAL<>HORIZONTAL with the same '''?''' are belong together.

:'''STEP:''' means how many steps in each section (0-127) > one step is 1/100 of a second!
:'''VERTICAL''': means how big is the step size from bottom to top (-128 to 127)
:'''HORIZONTAL''': means how big is the step size from left to right (0-255)

==== <code>ENV ‹volume envelope number›[,‹volume env. section›][,‹volume env. section›][,‹volume env. section›][,‹volume env. section›][,‹volume env. section›]</code> ====
:The ENV command define the VOLUME shape of a sound which means manipulating the loudness in a certain range.
:The command could looks like:
<pre>
ENV NUMBER,STEPS?,VERTICAL?,HORIZONTAL?
</pre>
:It is possible to define 15 different envelope shapes. So '''NUMBER''' could be 1-15.

:Each '''?''' stands for up to five sections (1-5), where each STEP<>VERTICAL<>HORIZONTAL with the same '''?''' are belong together.

:'''STEP:''' means how many steps in each section (0-127) > one step is 1/100 of a second!
:'''VERTICAL''': means how big is the step size from bottom to top (-128 to 127)
:'''HORIZONTAL''': means how big is the step size from left to right (0-255)

==== <code>ERASE v1[% | ! | $][,v2[% | ! | $][,...]]</code> ====
: Erases the specified array(s) and frees the memory used. Must specify existing array(s) or an <code>Improper argument</code> error will be generated.

==== <code>ERL</code> ====

: Returns the line number of the last error encountered.

==== <code>ERROR i</code> ====
: Returns the error message whose error code number is i.

==== <code>EVERY i[,t] GOSUB ln</code> ====

: BASIC branches to the subroutine at line ln EVERY (reccuring) i/50 seconds. (see also "AFTER i[,t] GOSUB line")

: There are 4 delay timers from 0 to 3 which can be specified with ‹timer number›. If omitted ‹timer number› defaults to 0.
: In the case of parallel task has 3 the highest and 0 the lowest priority.
: With DI or EI you can disable or enable the timing interrupt. With REMAIN <timer number> you can also disable an AFTER or EVERY construct and stores the "remaining" time (> REMAIN)
: Interrupts run as long as the main loop / program runs, even the main programm is paused > press ESC only '''once''' not twice for a break.
: It is important to know or realise that low-priority-interrupts which occurs simultanously to higher-priority-interrupts are not lost. Their task remains or handled again after finishing the higher-prio interrupt.

<pre>
10 REM > interrupts
20 EVERY 50,0 GOSUB 100: REM > lowest priority
30 EVERY 100,1 GOSUB 200
40 EVERY 200,2 GOSUB 300:
50 AFTER 1000,3 GOSUB 400: REM > highest priority
60 WHILE flag=0
70 a=a+1:print a
80 WEND
90 END
100 REM #0
110 PEN 2:PRINT "timer 0":PEN 1
120 RETURN
200 REM #1
210 PEN 2:PRINT "timer 1":PEN 1
220 RETURN
300 REM #2
310 PEN 2:PRINT "timer 2":PEN 1
320 RETURN
400 REM #3
410 flag=1:PEN 2:PRINT "no more interrupts..."
420 RETURN
</pre>

: Hint: Timing with interrupts is important, especially if more than one interrupts run. If the interval of a subroutine driven by an interrupt is too long than the processor can never get back to deal the main program again. Work out timing by measuring the subroutine or by trial and error.
: There are system internal interrupts (highest level) which cannot be influenced by BASIC interrupts (e.g. keyboard scan > BREAK key.)
: The next level of sytem internal interrupts CAN be influenced by BASIC interrupts. For example the sound queue which will be created by "ON SQ <chanel> GOSUB <line>". Those sound interrupts have an independent time tricker but their priority is parallel to the second priority times of BASICs interrupts. Therefore interrupts with timer 3 could "interrupt" them.

==== <code>FILL i</code> ====
: Fills an area of a graphics screen i colour i (0-15). Default value of i is the current graphics pen colour. Only available in Basic 1.1.

==== <code>FN</code> ====
:BASIC allows the program to define and use simple value returning functions. DEF FuNction is the definition part of this mechanism and creates program-specific function which works within the
:program in the same way as a function such a COS operates as a built-in function of BASIC. It may be invoked throughout the program. Variable types must be consistent and the DEF FN
:command should be written in part of the program outside the execution loop.

:Syntax : <code>DEF FN<name>[(<formal parameters>)]=<general expression></code>

:Example: ''"with the definition of..."''
<pre>
10 gn=9.80665
20 DEF FNgrv=s0+v0*t+0.5*gn*t^2
30 s0=0:v0=0:t=5
40 PRINT "...after";t;"seconds your dropped stone falls";FNgrv;"metres"
</pre>
:''"the results are..."''
<pre>
:...after 5 seconds your dropped stone falls 122.58315 metres
</pre>

==== <code>FOR TO STEP NEXT</code> ====
: Creating a counting loop (control strucutre) with a starting condition. Inside the counting loop one or more commands will be executed.
: The loop consists of of following specifications:

: 1. FOR
: 2. ''a control variable''
: 3. =
: 4. ''starting value''
: 5. TO
: 6. ''target value''
: 7. STEP [optional]
: 8. ''increment / step size''
: ''... instructions between''
: 9. NEXT
: 10. ''control variable'' [optional]

: You have to use the command STEP if you wish to count backwards. It's good to name the ''control variable'' after NEXT for readability and better program style.
: After each loop the computer checks internaly if the ''target value'' has been reached (like an IF ... THEN ... ELSE instruction). If the target value is reached NEXT closes the loop and calculates another step, so the ''control variable'' will be changed last time.
: The default STEP value - if not specified - is one (1).

: Example:
<pre>
10 FOR I=1 TO 10
20 PRINT I;
30 NEXT I
40 PRINT I
RUN
1 2 3 4 5 6 7 8 9 10 11
READY
</pre>

==== <code>FRAME</code> ====
: Smooths character and graphics movement and reduces flicker (waits for a VSYNC signal). Only available in Basic 1.1. On a CPC 464 you can use CALL &BD19 instead.

==== <code>GOSUB i</code> ====

: Jumps to subroutine which is given as argument.
: ''Example:''

<pre>
10 PRINT "Calling subroutine"
20 GOSUB 100
30 PRINT "Back from subroutine"
40 END
100 REM Begin of the subroutine
110 PRINT "Subroutine started"
120 RETURN
</pre>

==== <code>GOTO i</code> ====
: Jumps to the line number which is given as argument.
: ''Example:''
<pre>
10 GOTO 100
20 REM not executed
30 REM not executed
100 PRINT "Hello World!"
</pre>
: GOTO is the simplest form of a jump or creating a loop '''without''' condition controll.
: ''Example: (unconditional and endless loop)''
<pre>
10 PRINT "#";
20 GOTO 10
</pre>
: Combine the GOTO command with an IF...THEN...ELSE instruction for creating a condition-controlled loop with the '''test at the end'''. Helpful because the Locomotive Basic has no practical DO...WHILE... loop.
: ''Example: (condition at the end)''
<pre>
10 I=1
20 PRINT I
30 I=I+1
40 IF I<25 THEN GOTO 20
50 END
</pre>

==== <code>GRAPHICS</code> ====
: ...works only in combination with the command <code>PEN</code> or <code>PAPER</code> to set the plotting/drawing pen or background colour.
: If the <code>TAG</code> command is used to set text at the graphics cursor <code>GRAPHICS PEN</code> or <code>GRAPHICS PAPER</code> instead of the regular <code>PEN</code> or <code>PAPER</code>is necessary to colour the text.

==== <code>IF THEN ELSE</code> ====
: Asks for a choice with the '''IF...THEN...ELSE''' statement.
: '''IF''' compares the entry condition in a logical way
: '''THEN''' contains instruction if the comparison is true
: '''ELSE''' contains instruction if it's false.
: '''Example:'''
<pre>
10 INPUT "guess a figure:",f
20 IF f=10 THEN PRINT "right": END: ELSE GOTO 10
</pre>
: In case of nested choices there's a possibility to that with an IF...THEN instruction but not very recommended:
<pre>
10 INPUT "guess a figure:",f
20 IF f=10 THEN PRINT "right": END: ELSE IF f<10 THEN PRINT "too small" ELSE PRINT "too big"
30 GOTO 10
</pre>
:Other nested structures like IF...THEN...'''ELSE...ELSE''' won't work first because the Locomotive Basic only looks after the first ELSE instruction found and can't execute more single commands as a block for a certain condition in comparision to e.g. "PASCAL" > begin...end-block, "C" > {...}-block.

==== <code>INK ‹pen›,‹colour›,[‹second colour›]</code> ====
: Used to set the colour palette for each of the 16 available inks.
: pen specifies the pen slot to use.
: colour specifies the system colour to use (0..27.)
: if the second colour is provided, Locomotive Basic will blink between the colour and second colour.
: In MODE 0, all 16 pens are available. In MODE 1, only 4 pens are available (0..3). In MODE 2, only 2 pens are available (0..1.)
: By default, pen 0 is the background colour and pen 1 is the foreground/text colour.
: Examples:
<pre>
10 MODE 2
20 INK 0,3: REM Set background colour to red
30 INK 1,26: REM Set foreground/text colour to white
</pre>

==== <code>INPUT[#‹stream expression›][,]</code> ====
: [...]

==== <code>KEY</code> ====
: [...]

==== <code>LET</code> ====
: Used to define variables. You don't need to use the ''LET'' command because it is just a command which was added for compatibility reasons.
: ''Example:''
<pre>
10 LET a$ = "hello world"
20 PRINT a$
</pre>

==== <code>LINE INPUT [#‹stream expression›][,]‹variable›[,‹variable›] </code>====
: [...]

==== <code>LIST [‹line number›][-[‹line number›]], [#‹stream expression›]</code>====
: A command for listing the Basic program code.
: Possibility for manipulating display is using line numbers with a minus symbol.
: Example:
<pre>
LIST 100-
</pre>
: List every line after line number 100.
<pre>
LIST -100
</pre>
: List every line until line number 100 has reached.
<pre>
LIST 100-200
</pre>
: List every line between line number 100 and 200 included

: With the help of separate window definitions it is possible to print out long listings, better differentiate parts / slices of it into different window predefined
: Example:
<pre>
LIST 1000-1100,#1
LIST 3000-3100,#2
</pre>
: ...prints out two parts of one program out into two windows (if they are defined well)

==== <code>LOAD ‹file name›[,‹address›] </code>====

With this directive you may load any file in memory

Basic files (extension .BAS) are loaded in Basic memory, you cannot choose loading address

Binary files are loaded to the default address location stored in the AMSDOS header but you may force loading address (&C000 for a screen)

TAPE convention:

When loading tape files, the basic display a message every block which may cause trouble. Message output may be disabled by using prefix "!" before the filename.

It's also possible to load the next file disregarding his name using only "!" => <code>LOAD "!"</code>

==== <code>LOCATE[#‹stream expression›][,] x,y</code> ====

: Moves the text cursor to the x,y location.

: x starts at 1 on the left and goes up to 20 (in mode 0), 40 (in mode 1) or 80 (in mode 2).

: y starts at 1 at the top and ends at 25 at the bottom.

==== <code>MASK [i1][,i2]</code> ====

: Sets bits in each adjacent group of 8 pixel on (1) or off (0) according to binary value of i1 (0-255). i2 determines whether the first point of the line is to plotted (1) or not (0).

:Example:

<pre>
10 CLG 2:MASK 1:MOVE 0,0:DRAW 500,400
20 MASK 15:MOVE 0,0:DRAW 500,400
</pre>

==== <code>MEMORY ‹memory address›</code> ====

: Allocates the amount of memory to be used by BASIC by setting the [[Locomotive_BASIC#HIMEM|address of the highest byte]] it may use.

==== <code>MERGE</code> ====
: [...]

==== <code>MID$ (‹string›,‹start position›[,‹length of substring›])</code> ====
: With the MID$ command there are two applications possible:

: 1. MID$ creates a new substring out of the give ‹string› and starts at the defined position ‹start position› and print the number of given characters by ‹length of substring›.
: If no length is defined every character from ‹start position› will be printed out.
: If a higher value of ‹start position› or ‹length of substring› than the real length of the initial string is defined a blank string will be printed.
: The range of ‹start position› or ‹length of substring› is from 0 up to 255 characters.

: 2. With MID$ you're able to manipulates given strings by inserting a new string.
: Take care of the two different applications and using in BASIC.

: Example for the 1. application:
<pre>
10 a$="Hello"
20 PRINT MID$(a$,2,2)
run
el
Ready
</pre>
:
: Example for the 2. application
<pre>
10 a$="Hello"
20 MID$(a$,2,3)="ipp"
30 PRINT a$
run
Hippo
Ready
</pre>

==== <code>MODE</code> ====
: Changes the screen mode: MODE 0 is 160×200 in 16 colours, MODE 1 is 320×200 4 colours, MODE 2 is 640×200 2 colours and MODE 3 is 160×200 in 4 colours.

==== <code>MOVE x,y [[,i1][,i2]]</code> ====

: Moves the graphic cursor to position x,y. The parameter i1 may be used to change the pen (drawing) colour. The parameter i2 specifies the logical colour, as in DRAW.

: 4 drawing styles:
<pre>
i2 = 0 normal colour
i2 = 1 XOR colour
i2 = 2 AND colour
i2 = 3 OR colour
</pre>

==== <code>MOVER xr,yr[,[i1][,i2]]</code> ====
: moves the graphic cursor (relative) from current position to current cursor x position + xr, current cursor y position + yr. i1 and i2 as in MOVE.

==== <code>NEW</code> ====
: Clears BASIC RAM which means program and variables. Keeps symbol defintion (if defined) and screen mode without clearing.

==== <code>ON BREAK CONT</code> ====

: Prevents the interruption of program execution by the ESC key.

==== <code>ON BREAK GOSUB ln</code> ====

: Passes control to subroutine at line ln when ESC ESC pressed.

==== <code>ON BREAK STOP</code> ====

: Restores normal function of ESC key during program execution.

==== <code>ON ERROR GOTO ln</code> ====

: Passes the control to line ln if an error is detected in the program.

: ON ERROR GOTO 0, Turns of the error trap, and restores normal error processing.

==== <code>ON variable GOTO ln x1, x2, x3, x4, ...</code> ====

: In case of passing more choices '''ON variable GOTO ln x1, x2, x3, x4, ...''' points to a table with the jumping target.
: '''Example:'''
<pre>
10 PRINT "1. LOAD - 2. SAVE - 3. EXIT"
20 INPUT choice
30 ON choice GOTO 1000, 2000, 3000
40 CLS: GOTO 10
1000 PRINT "1. LOAD":END
2000 PRINT "2. SAVE":END
3000 END
</pre>
:In case that the variable ''choice'' won't fullfil the condition (in a range between line 0 and 65535) the next instruction will be executed (here: Line 40). If "choice" is smaller than 0 an error will occur.

==== <code>ON variable GOSUB ln x1, x2, x3, x4, ...</code> ====

: In case of passing more choices targeting to SUBROUTINES '''ON variable GOSUB ln x1, x2, x3, x4, ...''' points to a jumping table.
: '''Example:'''
<pre>
10 PRINT "1. LOAD - 2. SAVE - 3. EXIT"
20 INPUT choice
30 ON choice GOSUB 1000, 2000, 3000
40 CLS: GOTO 10
1000 PRINT "1. LOAD":RETURN
2000 PRINT "2. SAVE":RETURN
3000 END
</pre>
:In case that the variable ''choice'' won't fullfil the condition (in a range between line 0 and 65535) the next instruction will be executed (here: Line 40). If "choice" is smaller than 0 an error will occur.

==== <code>ON SQ(x) GOSUB ln x1, x2, x3, x4, ...</code> ====
:ON SQ(x) can trigger an interrupt when e.g. a space or free channel in queue.
:Using that command is a one way interrupt trigger and shouldn't be mixed with <code>EVERY</code> or <code>AFTER</code> commands.

:See also the <code>SQ(x)</code> command for more details.

==== <code>OPENIN ‹filename›</code> ====
: Opens the specified data file for reading. It has to be an ASCII file. ( The command <code>CLOSEIN</code> closes reading data file. )
: Read from the file using <code>INPUT #9</code>

==== <code>OPENOUT ‹filename›</code> ====
: Opens the specified data file for writing. It writes an ASCII file. (To close writing use the command closein.)

==== <code>ORIGIN x,y[,l,r,t,b]</code> ====
: The command defines the origin ('world reference point') for the graphics coordinate system. Normally the reference origin is in the left, bottom corner of the default screen and has 0,0. So the most left coordinate value could be by default 639 and the most top value 399. Independent from the actual modus (2, 1 or 0) the range for the x coordinate are always 640 points and for the y coordinate 400 points. In theory you are able to address 256,000 pixel but only 128,000 are visible due to the maximal resolution of the hardware.
: <code>x,y</code> are the the new coordinates for the 'world reference '.
: <code>l,r,t,b</code> are optional and set the borders for the new graphical window (works in the same way like the <code>WINDOW</code> command for a text window). l,r,t,b means left, right, tob and bottom coordinates.
: If a new graphical window (borders) is defined every point or drawn line won't be plotted (clipped internally).

: Example (the line drawn will be cutted):
<pre>
ORIGIN 320,200,250,450,100,300
DRAW 0,200
</pre>

==== <code>OUT ‹address›,‹value›</code> ====

: Outputs a value (range of 0-255) to a specific I/O address.
: Watch out http://cpcwiki.eu/index.php/I/O_Port_Summary

==== <code>PAPER[#‹stream expression›][,]</code> ====
: [...]

==== <code>PEN[#‹stream expression›][,]</code> ====
: [...]

==== <code>PLOT</code> ====
: [...]

==== <code>PLOTR</code> ====
: [...]

==== <code>POKE add</code> ====

: Alters contents of memory location add to value i (0-255)

==== <code>PRINT[#‹stream expression›][,]</code> ====
: [...]

==== <code>RAD</code> ====
: Switch to radians mode for trigonometric functions (<code>SIN</code>, <code>COS</code>...).

: ''See also:'' <code>DEG</code>

==== <code>RANDOMIZE [seed]</code> ====

: Resets the pseudo-random generator to the given seed (starting value of the 'random' series). What is strange is that if no seed is given, one is interactively prompted for.

: A common idiom to have a ''random'' random seed is to do:

<pre>
RANDOMIZE TIME
</pre>

: <code>RANDOMIZE TIME</code> isn't still a 'real' random number but to hit the same series again is pretty hard due to the time elapsed.
: The algorithm used for randomizing is the following: the generator starts with the seed, adds 1, multiplies by 75 (fiddle factor), divides by 65537 and then uses the remainder -1.

==== <code>READ variable</code> ====
: Gets the next data item (from <tt>DATA</tt> commands), stores it in the given variable and moves to the next item.
The variable must be of the correct type.

''See also:'' <tt>DATA</tt>, <tt>RESTORE</tt>

==== <code>RELEASE chanel</code> ====
: Releases a sound which was hold on (by a SOUND command) before. It uses the same bit matrix like the SOUND command for the first parameter
# (&x00000001) releases chanel A
# (&x00000010) releases chanel B
# (&x00000011) releases chanel A and B
# (&x00000100) releases chanel C
# (&x00000101) releases chanel A and C
# (&x00000110) releases chanel B and C
# (&x00000111) releases chanel A, B and C

:Example:
<pre>
10 SOUND 65,1000,100
20 PRINT"PRESS R TO LET IT SOUND"
30 IF INKEY(50)=-1 THEN 30
40 RELEASE 1
</pre>

==== <code>REM [any text]</code> ====
: Introduces a comment.

==== <code>RENUM [‹newLine›][,‹oldLine› | ,[‹oldLine›],‹step›] </code>====
: Renumbers the lines of the current program.

: By default, the whole program is renumbered starting at line 10 with multiples of ten. Any parameter that is left out defaults to 10. It is important to note that ''jumps'' (<code>GOTO</code>, <code>GOSUB</code> and the like) are automatically converted to the new line numbers.

: The whole set of parameters can be used to renumber only the last part of a program.

: Example:

<pre>
10 GOTO 20
20 GOTO 30
30 GOTO 10
</pre>

: becomes, after calling <code>RENUM 100,20,5</code>

<pre>
10 GOTO 100
100 GOTO 105
105 GOTO 10
</pre>

==== <code>RESTORE [line]</code> ====

: Resets the data pointer used by <tt>READ</tt>. When used without parameters, resets the pointer to the first data in the program. Otherwise, resets the pointer to the given line number.

: Example:

<pre>
10 DATA 10,11,12,13,14
20 DATA 20
READ i:PRINT i
10
Ready
READ i:PRINT i
11
Ready
RESTORE
Ready
READ i:PRINT i
10
Ready
RESTORE 20
Ready
READ i:PRINT i
20
Ready
</pre>

: ''See also:'' <tt>DATA</tt>, <tt>READ</tt>

==== <code>RESUME [line] or NEXT</code> ====
: Command causes the program to resume after an error code and if it is interrupted by an '''ON ERROR GOTO''' jump
: So it can either resume
*(if there's no line number stated) at the same line after error code (and if there are more statements in one line)
or
* at the line number stated (optional)
or
* with the NEXT parameter (optional) ... at the line followed by the error line

==== <code>RETURN</code> ====

: Terminates a subroutine and returns control to the line following the GOSUB call (see GOSUB)

==== <code>RUN [line] or "filename"</code> ====
:Runs the current program, optionally starting at a given line. If no line number is given, starts at the first line.

:If a string is used after RUN command a programm will be loaded and executed from storage medium (e.g. Tape, Disc). With that command protected BASIC programs can be executed.

:Exampel:
<pre>
RUN"disc"
</pre>

==== <code>SAVE "filename" [,filetype][,paramter1,parameter2,parameter3]</code> ====
: Command saves the current BASIC program / content from RAM onto a storage medium (e.g. Tape, Disc)

: Filetype could be:
* ''',A''' for a ASCII file
* ''',B''' for a binary file (store RAM content as it is)
* ''',P''' for a regular, ''protected'' BASIC file
: without that parameter the content will be stored as a regular BASIC file

:The three parameters after filetype could be used in combination with the binary filetype (,B).
* '''''parameter1''''' defines the starting address of memory range
* '''''parameter2''''' defines the length (range of memory)
* '''''parameter3''''' defines the entry point (optional)

==== <code>SOUND</code> ====
: the SOUND command has following shape:
: SOUND '''C'''hannel,'''P'''eriod,'''D'''uration,'''V'''olume,Volume-'''Env'''elope,'''T'''one-'''En'''velope,'''N'''oise

:'''C:''' Selecting channel is done bitwise (combinations are possible of course):

<pre>
(Bit 0) &x00000001 = 1 = channel A (middle)
(Bit 1) &x00000010 = 2 = channel B (left)
(Bit 2) &x00000100 = 4 = channel C (right)
</pre>
:more function about channel are
<pre>
(Bit 3) &x00001000 = 8 = Rendezvous with channel A
(Bit 4) &x00010000 = 16 = Rendesvous with channel B
(Bit 5) &x00100000 = 32 = Rendesvous with channel C
(Bit 6) &x01000000 = 64 = Hold
(Bit 7) &x10000000 = 128 = Flush
</pre>
:'''P:''' the period number can be a figure between 0 and 4095 (2^12-1... 12 means that we have 12 tones (inclusive half-tones) in nine octaves on the CPC in sum and their distance between is the twelves square root of two), where 8 octaves are available. E.g. Octave 0 starts on middle C with number 478.
: To calculate the period you can use following formula: '''period=1,000,000/(16*frequency)''' or in short '''period=(62,500/frequency)'''
: (e.g. the note "A" with the frequency 440 Hz has the period 142 on the CPC)

:'''D:''' the duration of the note is measured in 1/100th of a second and can be any positive number in the range 1-32,767. 0 and negative number are in combination with ENT and ENV commands usefull. A negative number means repititions.

:'''V:''' the volume number range from 0-7 on a CPC 464 (BASIC 1.0) or 0-15 on a CPC664/6128 (BASIC 1.1)

:'''ENV:''' and '''ENT:''' For shaping the sound ENV (Volume) and ENT (Frequency) commands are available. The relation between SOUND and those commands comes with a figure between 1 to 15 for ENV (5th parameter) and 1 to 15 for ENT (6th parameter).

:'''N:''' the seventh parameter can be used for blending in noise between the range of 0-15 (BASIC 1.0) or 0-30 (BASIC 1.1). The higher the number the 'deeper' or 'dirty' is the noise.

==== <code>SPC <n></code> ====
: in conjunction with PRINT the SPC command prints out a certain number (n) of spaces.
: Example:
<pre>
PRINT "Hello";SPC(10);"World";
Hello World
</pre>

==== <code>SPEED INK <n1,n2> </code> ====
: SPEED INK command defines the frequency of colour changes if a colour change was defined. The duration is calculated by n1=... or n2 =duration/50 seconds.

==== <code>SPEED KEY <start,repeat> </code> ====
: SPEED KEY command defines the delay after which a key repeat (for keys that do repeat). The first parameter is the delay before the first repeat and the second parameter is the delay between further repeats. Delay is in 1/50th of seconds.

:When using it with low values, it is common to associate a key to reset the default speed of 30,2.
:For example to associate the key 0 from the numpad:
<pre>
KEY 0,"SPEED KEY 30,2"+CHR$(13)
</pre>

==== <code>SPEED WRITE <n> </code> ====
: SPEED WRITE defines the speed at which data is to be saved or written to a cassette unit. n=1 means 2000 baud, n=0 (default) means 1000 baud. When reading from the tape, the correct speed is automatically selected.

==== <code>SQ (channel)</code> ====

: Returns a bit significant integer showing state of the sound queue for specified channel where channel 1,2,3, = A, B, C

:Bits 0,1 and 2 Number of free entries in the queue
:Bits 3,4 and 5 Redezvous state at head of the queue
:Bit 6 Head of the queue is held
:Bit 7 Channel is currently active

==== <code>STOP</code> ====

: Breaks program execution at line containing the STOP statement. The message '''BREAK in''' is output with the line number.

==== <code>SWAP</code> ====
: SWAP works only in combination with the window command. Every error or status messages from the operating system will be displayed normaly on WINDOW#0 (=''main'' window). WINDOW SWAP changes the ''main'' window to the desired target window.
: Example (if a window with number 4 was defined before...):
<pre>
WINDOW SWAP 0,4
</pre>

==== <code>SYMBOL n,i1[,i2,i3,i4,i5,i6,i7,i8]</code> ====

: Redefines the appearance of the character at index n.
: Each of the following eight integers defines the contents of one pixel row, starting at the top of the character.
: Each character fits in an 8x8 pixel grid.
: Missing lines are considered as empty.

: Example:

<pre>
SYMBOL 255,255,129,129,129,129,129,129,255
PRINT CHR$(255)
</pre>

: Defines character 255 to look like an empty square and prints it.

: Initially, only characters with indices ranging from 240 to 255 can be redefined.
: See also <tt>SYMBOL AFTER</tt> to allow redefinition of arbitrary characters.

==== <code>SYMBOL AFTER n</code> ====
: Allows the redefinition of character symbols from index n included.

: Symbol redefinitions are made using the SYMBOL command above.
: Initially, only symbols from index 240 to 255 can be redefined. This initial situation can be restored with <tt>SYMBOL AFTER 240</tt>. Symbol previously redefined are restored to their original appearance.

==== <code>TAB</code> ====
: [...]

==== <code>TAG [#st]</code> ====

: Allows text to print at graphics cursor position.
: see TAGOFF

==== <code>TAGOFF [#st]</code> ====

: Directs text to stream st printing it at previous text cursor position.

==== <code>TROFF</code> ====

: Turns off the program flow trace (see TRON)

==== <code>TRON</code> ====

: Turns on the program flow trace for debugging. Causes the line number of each statement executed to be displayed.

==== <code>USING</code> ====
: The USING assignement defines the format of the PRINT output. Its appointment happens by characters where each has a certain meaning.

'''Numbers / Figures'''
: the character:
:'''#''' stands for a figure between 0 - 9
:'''.''' stands for a decimal point
:'''+''' generates a positive sign if the value is positive
:'''-''' generates a negative sign if the value is nagative
:'''**''' generates a asterix for each empty "location" before the printed character
:'''$$''' generates a Dollar characters before the printed character (the same with the pound note)
:''',''' generates a comma every each three decimals (thousands per figure) and has to be set before the decimal point or at the end if without a decimal point.
:^ generates a scientific notation (with exponents) and a the end of the format appointment

'''Strings'''
: the character:
:'''!''' prints out only the first character
:'''\xxx\''' prints out only with x-numbers defined length of the string (from left to right). x means a blank sign made with the space bar
:'''&''' the whole string is printed out as given (unknown function)

: a print output (numbers) with "%" in the beginning shows that not enough positions has to be declared (at all or before the decimal point).

: Example:
<pre>
10 figure=123456789
20 word$="Hello"
30 print using "+**,##########";figure
40 print using "\ \";word$

creates following output:

*****+12,345,679
Hel
</pre>

==== <code>WAIT add, i1[,i2]</code> ====

: Waits until the I/O port at add returns a value (0-255). The value returned is XORed with i2 and the ANDed with i1. This is repeated until a non-zero result occurs.

==== <code>WHILE WEND</code> ====
: [...]

==== <code>WIDTH</code> ====
: [...]

==== <code>WINDOW[#‹stream expression›],[L],[R],[T],[B]</code> ====
: It is possible to define in BASIC eight (8) independent windows for text output. Overlapping is possible.

: #STREAM: eight window are possible. No. zero (0) is the main window where error or status messages were put out by default.
: each position is included inside the window
: L = left column / R = right column (dependent of the mode 0 = 20 / 1 = 40 / 2 = 80)
: T = top row / B = bottom row (always from 1 to 25)

: Example:
<pre>
MODE 1
WINDOW#1,1,40,1,6
</pre>
: ...defines the first top quarter of the screen for window No. 1

==== <code>WRITE [#st,] v[$], v[$]</code> ====

: Writes the values of the specified variable to the specified stream.

: Example:

<pre>
10 OPENOUT "DUMMY"
20 INPUT A$,A
30 WRITE #9,A$,A
40 CLOSEOUT
</pre>

==== <code>ZONE i</code> ====

: Changes the width of the print zone. Default is 13.
: Example:
<pre>
10 MODE 2
20 PRINT"normal zone (13)"
30 PRINT 1,2,3,4
RUN
normal zone(13)
1 2 3 4
READY
20 PRINT"now with different zone(5)"
30 ZONE 5
40 PRINT 1,2,3,4
RUN
now with different zone(5)
1 2 3 4
READY
</pre>

=== Operators ===
: A logical status in Locomotive Basic will be represented by a "-1" for TRUE and by a "0" for FALSE.
: Example:
<pre>
PRINT (1=1)
-1
PRINT (1=2)
0
</pre>
==== <code>AND</code> ====
: Possible combinations with the AND Function:
<pre>
NPUT1 INPUT2 OUTPUT
======================
TRUE TRUE TRUE
FALSE FALSE FALSE
TRUE FALSE FALSE
FALSE TRUE FALSE
</pre>
: Example:
<pre>
PRINT 128 AND 64
0
</pre>
: looking at the BIT combination for a better understanding:
<pre>
10000000
AND 01000000
================
= 00000000
</pre>
: even in BASIC it is possible to manipulate single BITs although there are no special commands but AND, OR and XOR.
: first an example for a loop with an increasing counter WITHOUT an AND:
<pre>
10 counter=0
20 counter=counter+1
30 IF counter=32 THEN counter=0
40 GOTO 20
</pre>
: then a shorter example WITH and AND:
<pre>
10 counter=0
20 counter=(counter+1) AND 31
30 GOTO 20
</pre>
: in the second example all more significant BITs will be deleted (a common method in assembler programming)
: Beware: it only works here with BIT/number conditions one figure smaller than 1, 3, 7, 15, 31, 63 and 127
==== <code>MOD</code> ====
: '''MOD''' returns a (rounded) rest (Modulos) after dividen has been devided by the devisor.
:
:'''Example:'''
<pre>
32767 mod 256
255
</pre>
: Note: only works with numbers in the range -32768 and 32767 (&8000 < 0 < &7FFF)

==== <code>NOT</code> ====
: '''NOT''' executes a bit for bit '''negation''' of the current value. The output is a 16-Bit-Word.
:
:'''Example:'''
<pre>
10 value1=1
20 value2=NOT value1
30 PRINT value2
run
-2
</pre>
:for a better understanding...
<pre>
10 value1=1
20 PRINT HEX$(value1):PRINT BIN$(value1,8)
30 value2=NOT value1
40 PRINT HEX$(value2):PRINT BIN$(value2,8)
run
1
00000001
FFFE
1111111111111110
</pre>

==== <code>OR</code> ====
: Possible combinations with the OR Function:
<pre>
NPUT1 INPUT2 OUTPUT
======================
TRUE TRUE TRUE
FALSE TRUE TRUE
TRUE FALSE TRUE
FALSE FALSE FALSE
</pre>
==== <code>XOR</code> ====
: Possible combinations with the XOR Function:
<pre>
NPUT1 INPUT2 OUTPUT
======================
TRUE TRUE FALSE
FALSE TRUE TRUE
TRUE FALSE TRUE
FALSE FALSE FALSE
</pre>

=== Functions ===

==== <code><big>ABS (<numeric expression>)</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Returns the ABSolute value of the given numeric expression (n). This means that negative numbers are returned as positive.
: '''Associated keywords''': SGN

: '''Example''':

<pre>
PRINT ABS(-67.98)
67.98
</pre>

==== <code><big>ASC (<string expression>)</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Returns the numeric value of the first character in the <string expression> (s).
: '''Associated keywords''': CHR$

: '''Example''':
<pre>
PRINT ASC("x")
120
</pre>
==== <code><big>ATN (<numeric expression>)</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Calculates the Arc-TaNgent of the <numeric expression> (n) to a real number ranging from -PI/2 to +PI/2 of the value specified.
: Note that DEG and RAD can be used to force the result of the below calculation to degrees or radians respectively.

: '''Associated keywords''': COS, DEG, RAD, SIN, TAN

: '''Example''':
<pre>
PRINT ATN(1)
0.785398163
</pre>
==== <code><big>BIN$ (<unsigned integer expression>,[<integer expression>])</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Produces a string of BINary digits respresenting the value of the <unsigned integer expression>, using the number of binary digits instruced by the second <integer expression> (in the range of 0 to 16). If the number of digits instructed is too great, the resulting expression will be filled with leading zeros; if the number of digits instructed is too small, the resulting expression will NOT be shortened to the instructed number of digits, but will produced in as many digits as are required.
: The <unsigned integer expression> to be converted into binary form must yield a value in the range -32768 to 65535.
: '''Associated keywords''': DEC$, HEX$, STR$
: '''Example''':
<pre>
PRINT BIN$(66,8)
01000000
</pre>
==== <code><big>CHR$ (<numeric expression>)</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Converts an <integer expression> in the range 0 to 255, to its CHaRacter $tring equivalent, using the AMSTRAD character set shown in the ASCII table or e.g. in the manual part 3.
: Note that 0 to 31 are control characters; hence the below example prints CHR$(x) in the range 32 to 255
: '''Associated keywords''': ASC, LEFT$, RIGHT$, MID$, STR$

: '''Example''':
<pre>
10 FOR X=32 to 255
20 PRINT X;CHR$(X);
30 NEXT
</pre>
: A further example, try the following basic program :
<pre>10 print chr$(208+rnd(2));:goto 10</pre>

: It will draw a random maze with characters 208 and 209, which are an horizontal and a vertical bar.

: Control Codes Table:
<pre>
===============================================================================
| VALUE | NAME | PARAMETERS | EFFECT |
===============================================================================
| DEC | HEX | | | |
===============================================================================
| 0 | &00 | NUL | NONE | DOES NOTHING |
| 1 | &01 | SOH | 0-255 | PRINTS CHARACTER TO SCREEN |
| 2 | &02 | STX | NONE | TURNS TEXT CURSOR OFF |
| 3 | &03 | ETX | NONE | TURNS TEXT CURSOR ON IN IMMEDIATE MODE |
| 4 | &04 | EOT | 0-2 | SET SCREEN MODE |
| 5 | &05 | ENQ | 0-255 | PRINT CHARACTER AT GRAPHICS CURS. |
| 6 | &06 | ACK | NONE | TURNS ON TEXT SCREEN (SEE ALSO CHR$(21))|
| 7 | &07 | BEL | NONE | MAKE A SHORT BEEP |
| 8 | &08 | BS | NONE | MOVES TEXT CURSOR BACK ONE CHARACTER |
| 9 | &09 | TAB | NONE | MOVES TEXT CURSOR FORWARD ONE CHARACTER |
| 10 | &0A | LF | NONE | MOVES TEXT CURSOR DOWN ONE CHARACTER |
| 11 | &0B | VT | NONE | MOVES TEXT CURSOR UP ONE CHARACTER |
| 12 | &0C | FF | NONE | CLEARS SCREEN OR WINDOWS (= CLS) |
| 13 | &0D | CR | NONE | MOVES CURSOR TO LEFT EDGE OF WINDOW ON |
| | | | | CURRENT LINE |
| 14 | &0E | SO | 0-15 | SETS PAPER COLOUR |
| 15 | &0F | SI | 0-15 | SETS PEN COLOUR |
| 16 | &10 | DLE | NONE | DELETES CHARACTER UNDER TEXT CURSOR |
| 17 | &11 | DC1 | NONE | CLEARS LINE FROM LEFT OF WINDOW UP TO |
| | | | | AND INCLUDING CURRENT CHARACTER |
| 18 | &12 | DC2 | NONE | CLEARS FROM CURRENT CHARACTER TO RIGHT |
| | | | | EDGE OF THE WINDOW |
| 19 | &13 | DC3 | NONE | CLEARS FROM START OF WINDOW UP TO AND |
| | | | | INCLUDING CURRENT CHARACTER |
| 20 | &14 | DC4 | NONE | CLEARS FROM CURRENT CHARACTER TO END OF |
| | | | | WINDOW |
| 21 | &15 | NAK | NONE | TURNS OFF TEXT SCREEN (SEE ALSO CHR$(6))|
| 22 | &16 | SYN | 0 AND 1 | TURNS TRANSPARENT OPTION OFF AND ON |
| 23 | &17 | ETB | 0-3 | SET GRPAHICS PLOTTING MODE |
| 24 | &18 | CAN | NONE | CHANGE TO INVERSE CHARACTER DISPLAYING |
| 25 | &19 | EM | NINE PARAM. | DEFINES A CHARACTER (= SAME AS SYMBOL) |
| | | | EACH 0-255 | |
| 26 | &1A | SUB | FOUR PARAM. | DEFINES A TEXT WINDOW (=SAME AS WINDOW) |
| | | | 1-80, 1-80 | FROM LEFT, RIGHT, TOP TO BOTTOM |
| | | | 1-25, 1-25 | FROM LEFT, RIGHT, TOP TO BOTTOM |
| 27 | &1B | ESC | NONE | DOES NOTHING ON SCREEN (PRINTER SIGNAL) |
| 28 | &1C | FS | THREE PARAM. | SETS INK COLOUR TO FLASH BETWEEN TWO |
| | | | 0-15, 0-32 | INK NO, COLOUR 1, COLOUR 2 |
| | | | 0-32 | |
| 29 | &1D | GS | TWO PARAM. | SETS BORDER COLOUR TO FLASH BETWEEN TWO |
| | | | 0-31, 0-31 | COLOURS |
| 30 | &1E | RS | NONE | HOMES CURSOR TO TOP LEFT OF SCREEN |
| 31 | &1F | US | TWO PARAM. | MOVES CURSOR TO CELL SPECIFIED BY TWO |
| | | | 1-80, 1-25 | PARAMETERS (=SAME AS LOCATE) |
===============================================================================
</PRE>

==== <code><big>CINT (<numeric expression>)</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Returns the value of the <numeric expression> (n), Converting it to a rounded INTeger in the range -32768 to 32767.

: '''Associated keywords''': CREAL, FIX, INT, ROUND, UNT

: '''Example''':
<pre>
10 n=1.9999
20 PRINT CINT(n)
run
2
</pre>
==== <code><big>COPYCHR$ (#stream)</big></code> ====
: : ''BASIC 1.1''
: '''FUNCTION''': COPies a CHaRacter from the current position in the stream (which MUST be specified). The below program copies a character from location 1,1 (top left), and reproduces it at location 1,20.
: If the character read is not recognized, a null string is returned.

: '''Associated keywords''': LOCATE

: '''Example''':
<pre>
10 CLS
20 PRINT "top corner"
30 LOCATE 1,1
40 a$=COPYCHR$(#0)
50 LOCATE 1,20
60 PRINT a$
</pre>
==== <code><big>COS (<numeric expression>)</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Calculates the COSinus of the <numeric expression> (n).
: Note that DEG and RAD can be used to force the result of the below calculation to degrees or radians respectively.

: '''Associated keywords''': ATN, DEG, RAD, SIN

: '''Example''':
<pre>
DEG
PRINT COS(45)
0.707106781
</pre>
==== <code><big>CREAL (<numeric expression>)</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Returns the value of the <numeric expression> (n), Converting it to REAL.

: '''Associated keywords''': CINT

: '''Example''':
<pre>
10 a=PI
20 PRINT CINT(a)
30 PRINT CREAL(a)
run
3
3.14159265
</pre>
==== <code><big>DEC$(<numeric expression>, <format template>)</big></code> ====
: ''BASIC 1.1''
: '''FUNCTIION''': Returns a DECimal string representation of the <numeric expression> (n), using the specified <format template> to control the print format of the resulting string.
: The format template may contain ONLY the characters:

: + - $ £ * # , . ^

: The use of these 'format field specifiers' is described under the keyword PRINT USING.

: '''Associated keyword''': BIN$, HEX$, PRINT USING, STR$

: '''Example''':
<pre>
PRINT DEC$(10^7,"££########,.##")
£10,000,000.00
</pre>
==== <code><big>DERR</big></code> ====
: ''BASIC 1.1''
: '''FUNCTION''': Reports the last error code returned by the disc filing system. The value of DERR may be used to ascertain the particular Disc ERRor that occurred. See the listing of error messages below.

: '''Associated keywords''': ERL, ERR, ERROR, ON ERROR GOTO, RESUME

: '''Example''':
<pre>
LOAD "xyz.abc"

XYZ .ABC not found
Ready
PRINT DERR
146
</pre>
: '''Table of Disc ERRor codes''':
: If AMSDOS has already reported an error, then bit 7 is set, hence the value of DERR is offset by 128.
<pre>
===============================================================================
| VALUE | DERR value | DESCRIPTION |
===============================================================================
| 0 | 0 or 22 | [ESC] has been pressed |
| 14 | 142 (128+14) | The stream is not in a suitable state. |
| 15 | 143 (128+15) | Hard end of file has been reached. |
| 16 | 144 (128+16) | Bad command, usually an incorrect filename. |
| 17 | 145 (128+17) | File already exists. |
| 18 | 146 (128+18) | File does not exists. |
| 19 | 147 (128+19) | Directory is full. |
| 20 | 148 (128+20) | Disc is full. |
| 21 | 149 (128+21) | Disc changed while file were open. |
| 22 | 150 (128+22) | File is Read/Only. |
| 26 | 154 (128+26) | Soft end of file has been detected. |
| | | |
===============================================================================
</pre>
: Other values returned by DERR originate from the disc controller and are bit significant, always with bit 6 set.
: The significance of each bit is as follows:
<pre>
===============================================================================
| BIT | Significance |
===============================================================================
| 0 | Address mark missing. |
| 1 | Not writable - disc is write protected. |
| 2 | No data - can't find the sector. |
| 3 | Drive not ready - no disc in the drive. |
| 4 | Overrun error. |
| 5 | Data error - CRC error. |
| 6 | Always set to 1 to indicate error from disc controller. |
| 7 | Set to 1 if error has already been reported by AMSDOS. |
===============================================================================
</pre>
==== <code><big>EOF</big></code> ====
: ''BASIC 1.1''
: '''FUNCTION''': Checks to see if end of specified file has been reached during input. Returns 0 (false) until the end of file, then -1 (true).

: '''Associated keywords''': OPENIN, CLOSEIN

: This '''example''' reads a file from disc and print it out on screen. Like the "TYPE" command in CP/M or "|TYPE,file" of the UTOPIA-ROM.
<pre>
10 OPENIN "text.txt"
20 WHILE NOT EOF
30 LINE INPUT#9,a$
40 PRINT a$
50 WEND
60 CLOSEIN
</pre>
==== <code><big>ERR</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Reports the number of the last ERRor encountered. See the table below of error messages. In the example below you will see that ERRor number 8 is a 'Line does not exist' error.

: '''Example''':
<pre>
GOTO 500
Line does not exist
Ready
PRINT ERR
8
</pre>
: NOTE: BASIC 1.0 (officially) describes error codes until 30 (without an attached floppy disc controller). 31 & 32 are floppy disc error codes.
: '''Table of ERRor codes''':
<pre>
========================================================================================
| VALUE | NAME | DESCRIPTION |
========================================================================================
| 1 |Unexpected NEXT |A NEXT command has been encountered while not in a |
| | |FOR loop, or the control variable in the NEXT |
| | |command does not match that in the FOR. |
| 2 |Syntax Error |BASIC cannot understand the given line because |
| | |a construct within it is not legal. |
| 3 |Unexpected RETURN |A RETURN command has been encountered when not in a |
| | |subroutine. |
| 4 |DATA exhausted |A READ command has attempted to read beyond the end |
| | |of the last DATA. |
| 5 |Improper Argument |This is a general purpose error. The value of a |
| | |function's argument, or a command parameter is |
| | |invalid in some way. |
| 6 |Overflow |The result of an arithmetic operation has over- |
| | |flowed. This may be a floating point overflow, in |
| | |which case some operation has yielded a value |
| | |greater than 1.7E^38 (approx.). Alternatively, this |
| | |may be the result of a failed attempt to change a |
| | |floating point number to a 16 bit signed integer. |
| 7 |Memory full |The current program or its variables may be simply |
| | |too big, or the control structure is too deeply |
| | |nested (nested GOUSBs, WHILEs or FORs). |
| | |A MEMORY command will give this error if an attempt |
| | |is made to set the top of BASIC's memory too low, or|
| | |to an impossible high value. Note that an open file |
| | |has a buffer allocated to it, and that may restrict |
| | |the values that MEMORY may use. |
| 8 |Line does not exist |The line referenced cannot be found. |
| 9 |Subcript out of range |One of the subscripts in an array reference is too |
| | |big or too small. |
| 10 |Array already dimensioned|One of the arrays in a DIM statement has already |
| | |been declared. |
| 11 |Division by zero |May occur in real division, integer division, |
| | |integer modulus or exponentiation. |
| 12 |Invalid direct command |The last command attempted is not valid in direct |
| | |mode. |
| 13 |Type mismatch |A numeric value has been presented where a string |
| | |value is required or vice versa, or an invalidly |
| | |formed number has been found in READ or INPUT. |
| 14 |String space full |So many strings have been created that there is no |
| | |further room available, even after 'garbage |
| | |collection'. |
| 15 |String too long |Strings exceeds 255 characters in length. May be |
| | |generated by appending strings together. |
| 16 |String expression too |String expressions may generate a number of |
| |complex |intermediate string values. When the number of these|
| | |values exceeds a reasonable limit, this error |
| | |results. |
| 17 |Cannot CONTinue |For one reason or another the current program |
| | |be restarted using CONT. Note that CONT is intended |
| | |for restarting after a STOP command, [ESC][ESC], |
| | |or an error, and that any alteration of the |
| | |program in the meantime makes a restart impossible. |
| 18 |Unknown user function |No DEF FN has been executed for the FN just |
| | |invoked. |
| 19 |RESUME missing |The end of the program has been encountered while |
| | |in error processing mode (i.e. in an ON ERROR GOTO |
| | |routine). |
| 20 |Unexpected RESUME |RESUME is only valid while in error processing mode |
| | |(i.e. in an ON ERROR GOTO routine). |
| 21 |Direct command found |When loading a file, a line without a line number |
| | |has been found. |
| 22 |Operand missing |BASIC has encountered an incomplete expression. |
| 23 |Line too long |A line when converted to BASIC internal-form becomes|
| | |too big. |
| 24 |EOF met |An attempt has been made to read past end of the |
| | |file input stream. |
| 25 |File type error |The file being read is not of a suitable type. |
| | |OPENIN is only prepared to open ASCII text files. |
| | |Similarly, LOAD, RUN, etc, are only prepared to |
| | |deal with file types produces by SAVE. |
| 26 |NEXT missing |Cannot find a NEXT to match a FOR command. A line |
| | |number accompanying this message indicates the FOR |
| | |command to which this error applies. |
| 27 |File already open |An OPENIN or OPENOUT command has been executed |
| | |before the previously opened file has been closed. |
| 28 |Unknown command |BASIC cannot find a taker for an external command, |
| | |i.e. a command preceded by a bar |. |
| 29 |WEND missing |Cannot find a WEND to match a WHILE command. |
| 30 |Unexpected WEND |Encountered a WEND when not in a WHILE loop, or a |
| | |WEND that does not match the current WHILE loop. |
| 31 |File not open |(see 'Disc ERRors above). |
| | |If access attempted when no file was open. |
| 32 |Broken in |(see 'Disc ERRors above). |
| | |If access attempted when no file was open. |
| | | |
| | |If value 31 or 32 are stated, DERR could be |
| | |interrogate to give more detailed information. |
| | |(see example below.) |
========================================================================================
</pre>
: '''Example for ERR 31 / 32''':
<pre>
10 ON ERROR GOTO 1000
20 OPENOUT "myfile.asc"
30 WRITE #9,"test-data"
40 CLOSEOUT
50 END
1000 amsdoserr=(DERR AND &7F):REM mask off bit 7
1010 IF ERR<31 THEN END
1020 IF ERR=31 THEN PRINT "are you sure you've typed line 20 correctly?":END
1030 IF amsdoserr=20 THEN PRINT "disc is full, suggest you use a new data disc":END
1040 IF amsdoserr=&X01001000 THEN PRINT "put a disc in the drive, then press a key":WHILE INKEY$="":WEND:RESUME
1050 END
</pre>
==== <code><big>EXP (<integer expression>)</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Calculates 'E' to the power given in the <numeric expression> (i), where 'E' is approximately 2,7182818-the number whose natural logarithm is 1.

: '''Associated keywords''': LOG

: '''Example''':
<pre>
PRINT EXP(6.876)
968.743625
</pre>
==== <code><big>FIX (<numeric expression>)</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Unlike CINT, FIX merely removes the part of the numeric expression, to the right of the decimal point, and leaves an integer result, rounding towards zero.

: '''Associated keywords''': CINT, INT, ROUND

: '''Example''':
<pre>
PRINT FIX(9.99999)
9
</pre>
==== <code><big>FRE (<numeric expression>/<string expression>)</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Establishes how much FREe memory remains unused by BASIC. The form FRE("") forces a 'GARBAGE COLLECTION' before returning a value for available space.
: NOTE: BASIC uses only the first 64K of the memory.

: '''Associated keywords''': HIMEM, MEMORY

: '''Examples''':
<pre>
PRINT FRE(0) or PRINT FRE("hello")
PRINT FRE("")
</pre>
==== <code><big>HEX$ (<unsigned integer expression>, <field width>)</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Produces a $tring of HEXadecimal digits representing the value of the <unsigned integer expression>, using the number of hexadecimal digits instructed by the <field width> (in the range 0 to 16). If the number of digits instructed is too great, the resulting expression will be filled with leading zeros; if the number of digits instructed is too small, the resulting expression will NOT be shortened to the instructed number of digits, but will be produced in as many digits as are required.
: The <unsigned integer expression> to be converted into hexadecimal form must yield a value in the range -32768 to 65535.

: '''Accociated keywords''': BIN$, DEC$, STR$, UNT

: '''Example''':
<pre>
PRINT HEX$(255,4)
00FF
</pre>
==== <code><big>HIMEM</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Returns the address of the Highest byte of Memory use by BASIC, (which may altered by e.g. the MEMROY command).
: Before resetting the highest byte of available memory using the MEMORY command, it is advisable to issue the 'command mm=HIMEM'. You will thereafter be able to return to the previous memory capacity by issuing the command: 'MEMORY mm'
: NOTE: BASIC uses only the first 64K of memory.

: Associated keywords: FRE, MEMORY, SYMBOL, SYMBOL AFTER.

: '''Example''':
...on a CPC464
<pre>
PRINT HIMEM
43903
</pre>
...on a CPC6128
<pre>
PRINT HIMEM
42619
</pre>
==== <code><big>INKEY (<integer expression>)</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': INterrogates the KEYboard to report which keys are being pressed. The keyboard is scanned every 0.02 (1/50) second.
: The function is useful for spotting whether a certain key is down or up, by detecting the returned value of -1 (which occurs regardless of [SHIFT] and [CONTROL] key status).
: The example below detects when [SHIFT] and V (key number 55) are pressed together, then ends the program. Refer the manual for the key numbers.

: '''Associated keywords''': CLEAR INPUT, INKEY$, JOY

: '''Example''':
<pre>
10 IF INKEY(55)<>32 THEN 10
20 PRINT "You've pressed [SHIFT] and V"
30 CLEAR INPUT
run
</pre>
: The state of [SHIFT] and [CONTROL] in conjunction with the key specified in the <integer expression> is identified as follows:
<pre>
==============================================================================
|Value returned |[SHIFT] |[CTRL] |Specified key |
==============================================================================
|-1 |ignored |ignored |up |
|0 |up |up |down |
|32 |down |up |down |
|128 |up |down |down |
|160 |down |down |down |
==============================================================================
</pre>
==== <code><big>INKEY$</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': INterrogates the KEYboard, returning the current $tring reflecting any key that is pressed. It provides operator interaction without hitting [ENTER] after every answer. If there is a key pressed, then the function responds. If no key is pressed, INKEY$ returns an empty string.
: In the example below, lines 40 and 70 tell the program to loop back to line 30 after interrogating the keyboard string.

: '''Associated keywords''': CLEAR INPUT, INKEY

: '''Example''':
<pre>
10 CLS
20 PRINT "Select Yes or No (Y/N)?"
30 a$=INKEY$
40 IF a$="" THEN 30
50 IF a$="y" OR a$="Y" THEN 80
60 IF a$="N" OR a$="n" THEN 90
70 GOTO 30
80 PRINT "You have selected YES": END
90 PRINT "You have selected NO":
run
</pre>
==== <code><big>INP (‹port number›)</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Returns the INPut value from the I/O address specified in the <port number>.

: '''Associated keywords''': OUT, WAIT

: Watch out http://cpcwiki.eu/index.php/I/O_Port_Summary

: '''Example''':
<pre>
PRINT INP(&FF00)
255
Ready
</pre>
==== <code><big>INSTR ([‹startposition›,]‹searched string›, ‹searched for string›)</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Searches the first <searched string> expression to find the first occurance of the <searched for string expression<, and reports the position of its occurance within the <searched string>. If the <searched for string> does not occur within the <searched string>, then 0 is reported.
: The position at which to start searching the <searched string> is optionally specifiable using the <start position> parameter which must yield an integer number in the range 1 to 255.

: '''Associated keywords''': none

: '''1. Example''':
<pre>
a$="ABCD":PRINT INSTR(a$,"C")
3
Ready
</pre>
: '''2. Example''':
<pre>
a$="Hello":IF INSTR(a$,"i")<>0 THEN PRINT "no" else a$
no
Ready
</pre>
: '''3. Example''':
<pre>
10 CLS
20 alphabet$="ABCDEFGHIJKLMNOPQRSTUVWXYZ"
30 INPUT "Enter a letter";a$
40 b$=UPPER$(a$)
50 PRINT b$;" is number";
60 PRINT INSTR(alphabet$,b$);
70 PRINT "in the alphabet.":PRINT
80 GOTO 40
run
</pre>
==== <code><big>INT (<numeric expression>)</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Rounds the number to the nearest smaller INTeger, removing any fractional part. Returns then same value as FIX for positive number, but returns one less than FIX for negative numbers which are not already integers.

: '''Associated keyword''': CINT, FIX, ROUND

: '''Example''':
<pre>
PRINT INT(3.99), INT(-3.99)
3 -4
</pre>
==== <code><big>JOY (<integer expression>)</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': The JOY function reads a bit significant result from the joystick in the <integer expression> (either 0 or 1).
<pre>
================================
|Bit | Value decimal |
================================
|0(up) | 1 |
|1(down) | 2 |
|2(left) | 4 |
|3(right) | 8 |
|4(fire 2) | 16 |
|5(fire 1) | 32 |
================================
</pre>
==== <code><big>LEFT$ (<string expression>, <required length>)</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Returns the number of characters (in the range 0 to 255) specified in the <required length> parameter (<integer expression>), after extracting them from the LEFT of the <string expression>. If the <string expression> is shorter than the <required length>, the whole <string expression> is returned.

: '''Associated keywords''': MID$, RIGHT$

: '''1. Example''':
<pre>
A$="ABCDEFG":PRINT LEFT$(A$,3) - prints ABC
</pre>
: '''2. Example''':
<pre>
10 CLS
20 a$="AMSTRAD"
30 FOR n=1 to 7
40 PRINT LEFT$(a$,n)
50 NEXT
run
</pre>
==== <code><big>LEN (<string expression>)</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Returns the total number of characters (i.e. the LENgth) of the <string expression>.

: '''Associated keywords''': none

: '''Example''':
<pre>
10 LINE INPUT "Enter a phrase";a$
20 PRINT "The phrase is";
30 PRINT LEN(a$);"characters long."
run
</pre>
==== <code><big>LOG (<numeric expression>)</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Calculates the natural LOGarithm (base of ''e'') of <numeric expression> which mustbe greater than zero.

: '''Associated keywords''': EXP, LOG10

: '''Example''':
<pre>
PRINT LOG(9999)
9.21024037
</pre>
==== <code><big>LOG10 (<numeric expression>)</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Returns the logarithm to base 10 of <numeric expression> which must be greater than zero.

: '''Associated keywords''': EXP, LOG

: '''Example''':
<pre>
PRINT LOG10(9999)
3.99995657
</pre>
==== <code><big>LOWER$ (<string expression>)</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Returns a new string expression which is a copy of the specified <string expression> but in which all alphabetic characters in the range A to Z are converted to lower case. Useful for processing input where the answers may come in mixed upper/lower case.

: '''Associated keywords''': UPPER$

: '''1. Example''':
<pre>
A$="AMSTRAD":PRINT A$="AMSTRAD":PRINT LOWER$(A$)
Amstrad
</pre>
: '''2. Example''':
<pre>
10 a$="SEE HOW THE LETTERS CHANGE TO ... NUMBERS 1234 NOT..."
20 PRINT LOWER$(a$+"LOWER CASE")
see how the letters change to ... numbers 1234 not... LOWER CASE
</pre>
==== <code><big>MAX (<list of: numeric expression>)</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Returns the MAXimum value from the <list of: numeric expression>s.

: '''Associated keywords''': MIN

: '''Example''':
<pre>
10 n=66
20 PRINT MAX(1,n,3,6,4,3)
run
66
</pre>
==== <code><big>MIN (<list of: numeric expression>)</big></code> ====
''BASIC 1.0 & 1.1''
: '''FUNCTION''': Returns the MINimum value from the <list of: numeric expression>s.
: '''Associated keywords''': MAX

: '''Example''':
<pre>
PRINT MIN (3,6,2.999.8,9,)
2.999
</pre>

==== <code><big>PEEK (<address expression>)</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Reports the contents of the Z80 memory location specified in the <address expression> which should be in the range &0000 to &FFFF (0 to 65535). In all cases PEEK will return the value at the RAM address specified (not the ROM), and will be in the range &00 to &FF (0 to 255)

: '''Associated keywords''': POKE

: '''Example''':
<pre>
10 MODE 1: ZONE 7
20 WINDOW 1,40,1,2:WINDOW #1,1,40,3,25
30 PRINT "memory-address"
40 LOCATE 20,1:PRINT "memory-contents"
50 FOR n=1 to 65535
60 p=PEEK(n)
70 PRINT #1,n,"(&";HEX$(n);")";
80 PRINT #1,TAB(20);p,"(&";HEX$(p);")"
90 NEXT
run
</pre>
==== <code><big>PI</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': The value of the ratio between the circumference and the diameter of a circle.

: '''Associated keywords''': DEG, RAD

: '''Example''':
<pre>
PRINT PI
3.14159265
</pre>
==== <code><big>POS (#<stream expression>)</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Reports the current horizontal POSition of the text cursor relative to the left edge of the text window. The <stream expression> MUST be specified, and does NOT default to #0.
: POS(#8) reports the current horizontal carriage position for the printer, where 1 is the extreme left hand edge.
: POS(#9) reports the logical position in the disc file stream, i.e. the number of printing characters sent to the stream since the last carriage return.

: '''Associated keywords''': VPOS, WINDOW
: '''Example''':
<pre>
10 MODE 1: BORDER 0:LOCATE 8,2
20 PRINT "use cursor left/right keys"
30 WINDOW 1,40,12,12:CURSOR 1,1
40 FOR n=1 TO 19:PRINT CHR$(9);:NEXT
50 IF INKEY(1)<>-1 THEN PRINT CHR$(9);
60 IF INKEY(8)<>-1 THEN PRINT CHR$(8);
70 LOCATE #1,2,24
80 PRINT #1,"text cursor ";
90 PRINT #1,"horizontal position = ";
100 PRINT #1,POS(#0):GOTO 50
run
</pre>
==== <code><big>REMAIN (<integer expression>)</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Returns count REMAINing count from the delay timer specified in <integer expression> (= timer number in the range 0 to 3), and disable it. If the delay timer was not enabled zero will be returned.

: '''Associated keywords''': AFTER, DI, EI, EVERY

: For the reason that REMAIN is no normal command but a "function" it is necessary in case of a proper functionality to link the command.
: an '''example''' in combination with an interrupt delay timer 1:
<pre>
PRINT REMAIN(1)
</pre>
: or to stop several/all interrupts at the same time...
<pre>
A=REMAIN(0)=REMAIN(1)=REMAIN(2)=REMAIN(3)
</pre>
: Hint: Take care of interrupts due to parallel working (the same cycle time) or if they are stopped with the BREAK key. Interrupts which were disabled for a certain time will be stored in buffer (for a maximum of 128 entries) and made up their task afterwards in the priorisation as declared.
: further '''example''':
<pre>
10 AFTER 500,1 GOSUB 40
20 AFTER 100,2 GOSUB 50
30 PRINT "program running":GOTO 30
40 REM this GOUSB-Routine will not be called as it is disabled in line 80
50 PRINT:PRINT "Timer 1 will now be ";
60 PRINT "disabled by REMAIN."
70 PRINT "Time-units remaining were:";
80 PRINT REMAIN(1)
run
</pre>
==== <code><big>RIGHT$ (<string expression>, <integer expression>)</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Returns the number of characters (in the range 0 to 255) specified in the <integer expression> (=required length) parameter, after extracting them from the RIGHT of the <string expression>. If the <string expression> is shorter than the <integer expression>, the whole <string expression> is returned.

: '''Associated keywords''': LEFT$, MID$

: '''Example''':
<pre>
10 MODE 1:a$="AMSTRAD computer"
20 FOR n=1 TO 16:LOCATE 41-n,n
30 PRINT RIGHT$(a$,n)
40 NEXT
</pre>
==== <code><big>RND [(<numeric expression>)]</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Returns the next RaNDom number in sequence if the <numeric expression> has a positive value or is not specified.
: If the <numeric expression> yields a value of zero, RND returns a copy of the last random number generated.
: If the <numeric expression> yields a negative value, a new random number sequence is started, the first number of which is returned.

: '''Associated keywords''': RANDOMIZE

: '''1. Example''':
<pre>
PRINT RND(0)
0.536703827
Ready
PRINT RND(1)
0.271940658
Ready
PRINT RND(0)
0.271940658
Ready
</pre>
: '''2. Example''':
: Example for generating an integer random number between 1 and 1000
<pre>
10 A=INT((RND(1)*1000)+1)
20 PRINT A
30 GOTO 10
</pre>
: '''3. Example''':
: For generating a random number between a lower and higher border
<pre>
10 INPUT "Low border",low
20 INPUT "High border",high
30 A=INT(RND(1)*(high-low))+low
40 PRINT A
</pre>
: '''4. Example''':
<pre>
10 RANDOMIZE
20 FOR x=1 TO -1 STEP -1
30 PRINT "rnd parameter=";x
40 FOR n=1 TO 6
50 PRINT RND(x)
60 NEXT n,x
run
</pre>

==== <code><big>ROUND (<numeric expression>[,<integer expression>])</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Rounds <numeric expression> to a number of decimal places or to the power of ten specified by <integer expression>. If <integer expression> less than zero, the <numeric expression> is rounded to give an absolute integer with <integer expression> number of zeros before the decimal point.

: '''Associated keywords''': ABS, CINT, FIX, INT
: '''1. Example''':
<pre>
PRINT ROUND(1562.357,2),ROUND(1562.375,-2)
1562.36 1600
</pre>
: '''2. Example''':
<pre>
10 FOR n=4 TO -4 STEP -1
20 PRINT ROUND (1234.5678,n)
30 PRINT "with integer expression";n
40 NEXT
run
</pre>
==== <code><big>SGN (<numeric expression>)</big></code> ====
: ''BASIC 1.0 & 1.1''
: FUNCTION: Determines the SiGN of the <numeric expression>. Returns -1 if <numeric expression> is less than 0, returns 0 if <numeric expression> = 0, and returns 1 if <numeric expression> is greater than zero.

: '''Associated keywords''': ABS

: '''Example''':
<pre>
10 FOR n=255 to -200 STEP -20
20 PRINT "SGN returns";
30 PRINT SGN(n);"for a value of";n
40 NEXT n
run
</pre>
==== <code><big>SIN (<numeric expression>)</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Calculates the Real value for the Sine of <numeric expression>, defaulting to the Radian (RAD) measure mode unless otherwise declared by a DEG command.

: '''Associated keywords''': ATN, COS, DEG, RAD, TAN

: '''Example''':
<pre>
10 CLS:DEG:ORIGIN 0,20
20 FOR n=0 to 720
30 y=SIN(n)
40 PLOT n*640/720,198*y:NEXT
50 GOTO 50
run
</pre>
==== <code><big>SPACE$(<integer expression>)</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Creates a string of spaces of the given length, (in the range 0 to 255) specified in the <integer expression>.

: '''Associated keywords''': SPC, STRING$, TAB

: '''Example''':
<pre>
10 MODE 1
20 PRINT "Put 9 spaces between me";
30 PRINT SPACE$(9);
40 PRINT "and you!"
run
</pre>
==== <code><big>SQ (<channel>)</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Reports the state of the Sound Queue for the specified <channel> which must be an integer expression, yielding one the values:
: 1: for channel A
: 2: for channel B
: 4: for channel C
: The SQ function returns a bit significant integer, comprising the following bit settings:
: Bit 0,1 and 2: the number of free entries in the queue
: Bit 3,4 and 5: the rendezvous state at the head of this queue
: Bit 6 : the head of the queue is held
: Bit 7 : the channel is currently active
: ... where Bit 0 is the least significant bit, and Bit 7 is the most significant bit.
: It can be seen, that if Bit 6 is set, Bit 7 cannot be set at the same time, and vice versa. Similarly if Bits 3, 4, or 5 are set, Bit 6 and 7 cannot be set.

: '''Associated keywords''': ON SQ GOSUB, SOUND

: '''Example''':
<pre>
10 SOUND 65,100,100
20 PRINT SQ(1)
run
67
</pre>
==== <code><big>SQR (<numeric expression>)</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Returns the SQuare Root of the specified <numeric expression>.

: '''Associated keywords''': none

: '''Example''':
<pre>
PRINT SQR(9)
3
</pre>
==== <code><big>STR$ (<numeric expression>)</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Converts the <numeric expression> to a decimal STRing representation.
: Useful for converting a number to a string in case of string manipulation. E.g. after converting a figure to a string then the most left character holds the sign: a minus in case the figure is negative and a space in case the figure is positiv.

: '''Associated keywords''': BIN$, DEC$, HEX$, VAL

: '''1. Example''':
<pre>
10 FIGURE=-1599
20 FIGURE$=STR$(FIGURE)
30 PRINT FIGURE$
-1599
</pre>
: '''2. Example''':
<pre>
10 FIGURE=1769
20 FIGURE$=STR$(FIGURE)
30 PRINT FIGURE$
1769
</pre>
: '''NOTE''': (there's a blank on the left-hand of the number "1769")
: If you want to add e.g. zero before the figure in case of a high score with fix digit-number then you're able to add zero(s) in front of a string instead of a figure.

: '''3. Example''':
<pre>
10 a=&FF:REM 255 hex
20 b=&x1111:REM 15 binary
30 c$="***"
40 PRINT c$+STR$(a+b)+c$
run
*** 270***
</pre>

==== <code><big>STRING$ (<length>,<character specifier>)</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Returns a string expression consisting of the <character specifier> repeated the number of time (in the range 0 to 255) specified in the <length>.

: '''Associated keywords''': SPACE$

: '''1. Example''':
<pre>
PRINT STRING$(40,"*")
****************************************
</pre>
: '''2. Example''':
<pre>
PRINT STRING(40,42)
****************************************
</pre>
: '''NOTE''': the <character specifier> 42 refers to the ASCII value of the character '*' and is also equivalent to PRINT STRING$(40,CHR$(42))
==== <code><big>TAN (<numeric expression>)</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Calculates the TANgent of the <numeric expression>, which must be in the range -200,000 to +200,000.
: '''NOTE''': DEG and RAD can be used to force the result of the calculation to degrees or radians respectively.

: '''Associated keywords''': ATN, COS, DEG, RAD, SIN

: '''Example''':
<pre>
PRINT TAN(45)
1.61977519
</pre>

==== <code><big>TEST (<x co-ordinate>,<y co-ordinate>)</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Moves the graphics cursor to the absolute position specified by the <x> and <y co-ordinate>s, and reports the value of the ink at the new location.

: '''Associated keywords''': MOVE, MOVER, TESTR, XPOS, YPOS

: '''Example''':
<pre>
10 CLS
20 PRINT "Your are using pen number";
30 PRINT TEST(10,386)
40 PRINT "Try changing PENs and MODEs";
50 PRINT "....then RUN again."
run
</pre>
==== <code><big>TESTR (<x offset>,<y offset>)</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Moves the graphics cursor by the amount specified in the <x> and <y offset>s relative to its current position, and reports the value of the ink at the new location.

: '''Associated keywords''': MOVE, MOVER, TEST, XPOS, YPOS

: '''Example''':
<pre>
10 MODE 0:FOR x=1 TO 15:LOCATE 1,x
20 PEN x:PRINT STRING$(10,143);:NEXT
30 MOVE 200,400:PEN 1
40 FOR n=1 TO 23:LOCATE 12,n
50 PRINT "pen";TESTR(0,-16):NEXT
run
</pre>
==== <code><big>TIME</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Reports the elapsed time since the computer was last switched-on or reset, (excluding periods when reading or writing to disc).
: Each second of real time is equal to the returned value = TIME/300.

: '''Associated keyword''': AFTER, EVERY, WEND, WHILE

: '''Example''':
<pre>
10 CLS:REM clock
20 INPUT "hour";hour
30 INPUT "minute";minute
40 INPUT "second";second
50 CLS:datum=INT(TIME/300)
60 WHILE hour<13
70 WHILE minute<60
80 WHILE tick<60
90 tick=(INT(TIME/300)-datum)+second
100 LOCATE 1,1
110 PRINT USING "## ";hour,minute,tick
120 WEND
130 tick=0:second=0:minute=minute+1
140 GOTO 50
150 WEND
160 minute=0:hour=hour+1
170 WEND
180 hour=1
190 GOTO 60
run
</pre>
==== <code><big>UNT (<address expression>)</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Return an integer in the range -32768 to +32767 which is the twos-complement equivalent of the unsigned value of the <address expression>.

: '''Associated keywords''': CINT, FIX, INT, ROUND

: '''Example''':
<pre>
PRINT UNT(&FF66)
-154
</pre>
==== <code><big>UPPER$(<string expression>)</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Returns a new string expression which is a copy of the specified <string expression> but in which all alphabetic characters in the range A to Z are converted to upper case. The function is useful for processing input which may come in mixed upper / lower case.

: '''Associated keywords''': LOWER$

: '''Example''':
<pre>
10 CLS: a$="my, how you've grown!"
20 PRINT UPPER$(a$)
run
</pre>
==== <code><big>VAL(<string expression>)</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Returns the numeric VALue, (including any negative sign and decimal point) of the first character(s) in the specified <string expression>.
:If the first character is not a number, then 0 is returned. If the first character is a negative sign or decimal point followed by non-numeric characters, a 'Type mismatch' error (13) will be reported.

: '''Associated keywords''': STR$

: '''1. Example''':
<pre>
PRINT VAL("-12.34x"),VAL("A-12")
-12.34 0
</pre>
: '''Exception''': if <se> starts with "&" + character (and it's between "A" and "F") the whole character will be handled like a hexadezimal numeric character (...often used in DATA Loaders). The returning numeric value is a  signed integer (16-Bit Word).
: '''2. Example''':
<pre>
PRINT VAL("&A")
10

PRINT VAL("&7FFF")
32767

PRINT VAL("&8000")
-32768
</pre>
: '''3. Example''':
<pre>
10 CLS: PRINT "I know my times tables!"
20 PRINT:PRINT "Press a key (1 to 9)"
30 a$=INKEY$:IF a$="" THEN 30
40 n=VAL(a$):if n<1 or n>9 then 30
50 FOR x=1 to 12
60 PRINT n;"X";x;"=";n*x
70 NEXT:GOTO 20
run
</pre>
==== <code><big>VPOS (#<stream expression>)</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Reports the current vertical POSition of the text cursor relative to the top of the text window. The <stream expression> MUST be specified, and does NOT default to #0.

: '''Associated keywords''': POS, WINDOW

: '''Example''':
<pre>
10 MODE 1:BORDER 0:LOCATE 8,2
20 PRINT "use cursor up/down keys"
30 WINDOW 39,39,1,25:CURSOR 1,1
40 LOCATE 1,3
50 IF INKEY(0)<>-1 THEN PRINT CHR$(11);
60 IF INKEY(2)<>-1 THEN PRINT CHR$(10);
70 LOCATE #1,3,24
80 PRINT #1,"text cursor ";
90 PRINT #1,"vertical position =";
100 PRINT #1,VPOS(#0):GOTO 50
run
</pre>
==== <code><big>XPOS</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Reports the current horizontal (X)POSition of the graphics cursor.

: '''Associated keywords''': MOVE, MOVER, ORIGIN, YPOS

: '''Example''':
<pre>
10 MODE 1:DRAW 320,200
20 PRINT "graphics cursor X position = ";
30 PRINT XPOS
</pre>
==== <code><big>YPOS</big></code> ====
: ''BASIC 1.0 & 1.1''
: '''FUNCTION''': Reports the current vertical (Y)POSition of the graphic cursor.

: '''Associated keywords''': MOVE, MOVER, ORIGIN, XPOS

: '''Example''':
<pre>
10 MODE 1:DRAW 320,200
20 PRINT "graphics cursor Y position = ";
30 PRINT YPOS
</pre>

== Other Basic Dialects available for the CPC ==

*[[BBC Basic]]
*[[C BASIC Compiler|CBASIC]]
*[[BASIC-E]]

== Technical Information ==

* [[Technical_information_about_Locomotive_BASIC]]

== Web links ==

* [http://www.sean.co.uk/books/amstrad/bforbasic.shtm Locomotive Basic Tutorial by Sean McManus]
* [http://rosettacode.org/wiki/Category:Locomotive_Basic Code examples at Rosetta Code]

* [http://cpctech.cpc-live.com/docs/basic.asm Disassembly of Locomotive BASIC v1.1]

[[Category:Programming]]
[[Category:BASIC| ]]
[[Category:CPC Internal Components]]
[[Category:Operating System| ]]
[[Category:Software]]
[[Category:Programming software| ]]

BIOS Kernel Timer/Event Functions

2023-05-03T23:05:53Z

Esesci: /* Kernel Timer/Event Functions */ Correct the total bit length of two 16-bit registers :)

== Interrupt Vectors ==
0038 300HZ INTERRUPT (RST7)
003B EXT_INTERRUPT_VECTOR
0066 GARBAGE (THERE'S NO [[NMI]] HANDLER IN ROM)

== Kernel Timer/Event Functions ==
B921 KL_POLL_SYNCHRONOUS
B92A KL_SCAN_NEEDED_664 ;force ticker on next IRQ (664 and up only)
BCD7 KL_NEW_FRAME_FLY ;in: HL=kaffc, DE=proc,B=prio,C=ROMcfg ;\vsync
BCDA KL_ADD_FRAME_FLY ;in: HL=kaffc ; 50Hz/60Hz
BCDD KL_DELETE_FRAME_FLY ;in: HL=kaffc, out: CY=0=failed ;/
BCE0 KL_NEW_FAST_TICKER ;in: HL=kaftc, DE=proc,B=prio,C=ROMcfg ;\fast
BCE3 KL_ADD_FAST_TICKER ;in: HL=kaftc ; 300Hz
BCE6 KL_DELETE_FAST_TICKER ;in: HL=kaftc, out: CY=0=failed ;/
BCE9 KL_ADD_TICKER ;in: HL=katc, DE=count, BC=reload ;\50Hz div
BCEC KL_DELETE_TICKER ;in: HL=katc, out: DE=count, CY=0=fail ;/count
BCEF KL_INIT_EVENT
BCF2 KL_EVENT
BCF5 KL_SYNC_RESET
BCF8 KL_DEL_SYNCHRONOUS
BCFB KL_NEXT_SYNC
BCFE KL_DO_SYNC
BD01 KL_DONE_SYNC
BD04 KL_EVENT_DISABLE
BD07 KL_EVENT_ENABLE
BD0A KL_DISARM_EVENT
BD0D KL_TIME_PLEASE ;out: hl=low, de=high (32 bits, incremented at 300Hz)
BD10 KL_TIME_SET ;in: hl=low, de=high (32 bits, incremented at 300Hz)
[[Category:BIOS]]

Programming methods used in games

2023-04-20T07:02:38Z

Esesci: /* Rasters */ Add 007 The Living Daylights to the list.

This section describes specific programming methods which are used in games and the games that use them.

=== Sampled Sound ===

Sampled music:
* Prehistorik 2
* Xyphoes Fantasy

The sampled speech is often stored as 4-bit values with 2 values packed into each byte. Each value is sent to one of the AY volume registers at a fixed rate.

Sampled speech:
* Chase HQ
* Bad Dudes vs Dragon Ninja
* Robocop
* Ghost Hunters
* Advanced Pinball Simulator

=== Rasters ===

[[Rasters]] is a colour changing effect.

Examples:

* Zynaps
* 007 The Living Daylights

=== Hardware Double Buffer ===

Most good CPC games use the hardware double buffer technique in order to display sprites and/or to scroll the play area smoothly.

In particular, two memory areas (instead of one) are reserved for the screen ram.

In each frame, one of the two screens is displayed while the other is not visible but is drawn to. After the draw is done, the screens are exchanged using the hardware, so that the previously invisible one is now visible and the previously visible one is invisible.

The exchange is done using the hardware specifically by changing the screen-offset, Reg 12 and 13 of the [[CRTC|CRTC]]).

This process is repeated.

The big advantage of this technique is that we can use a whole frame (or more) machine-time for our code (with no problems that arise when we alter screen ram at the same time the electron beam displays it on the monitor such as tearing or flickering).

However, page flipping eats up a lot of memory area (which is crucial especially for 64Kb machines). This explains why a lot of games can have small game-areas !

For example:
Pac-Man Emulator

=== Scrolling ===

The following types of scroll are used:

1. The player controls a character on the screen. When the character is moved the screen scrolls but the character remains in the same position on the screen. If they get to the edge of the map, they may walk up to the sides of the screen. If they walk back the other way when they reach a particular point on the screen it starts to scroll again and they remain in the same position.

2. The player controls a character on the screen. When the character is moved towards the edges of the screen, the scroll moves a whole screen in width or height. The character is now on the opposite side. e.g. the character moves left, the screen scrolls by a whole screen width, the character is now on the right. The screen only scrolls when they get close to the sides.

3. The screen always scrolls. The player controls a character who is either static or moves freely around the screen.

=== Parallax/Multi Layer Scroll===

Parallax or Multi Layer Scroll is an effect where there are 2 layers of tiles which scroll, one has priority over the other and often they move at different scroll rates.

For example, the following games have parallax or multi layer scroll:

* Wizard Willy
* Teenage Mutant Hero Turtles
* Astro Marine Corps (AMC)
* Turrican I and II
* Shadow Dancer

==== Software Scrolling ====

The screen is scrolled using the CPU only. This can be done by moving the data on the screen, or re-drawing it in a different position to give the illusion of scrolling.

Examples:

* Robocop
* Batman the Movie.

==== Hardware Scrolling ====

Hardware scrolling is performed by changing the CRTC registers R12 and R13 to define the start address of the screen. The display is automatically wrapped at 16K, so continuous incrementation of these values will scroll the screen and wrap around. The code must then update the display for new graphics.

The scrolling is in CRTC character sizes.
* 1 CRTC char horizontally is 2 bytes of RAM at a time which corresponds to 4 mode 0 pixels, 8 mode 1 pixels or 16 mode 2 pixels.
* The height of a CRTC char is defined by CRTC Register 9 (Max Raster), which is normally set to 7. Resulting in 8 scanlines per character.

Horizontal scrolling can be made smoother by using R3 (Hsync Width), in addition to using R12 and R13 and makes the scrolling effectively half a CRTC char (therefore 2 mode 0 pixels, 4 mode 1 pixels or 8 mode 2 pixels). This can be done by changing the HSYNC width values between 5 and 6. The movement is an effect of how the monitor handles the HSYNC. This effect works well on Amstrad monitors, doesn't work on modern TFT screens and produces a black and white image on a MP-2 modulator because of the adjusted HSYNC timing.

Vertical scrolling can be made smoother by using R5 (Vertical Adjust). This works on all monitors.

More recent games (e.g. Prehistorik 2, Super Cauldron) use the rupture technique when doing vertical scroll to ensure the display is a constant number of scan lines in height, and so the refresh rate is always the same.

Older games adjust R5 and don't use rupture (e.g. LED Storm, Legend of Kage), the time for a frame therefore varies by up to 7 extra scan-lines. This means the VSYNC to the monitor also varies in position by up to 7 extra scan-lines, and the stability of the image is then dependent on how the monitor handles the VSYNC.

If the game uses a status panel, there are 2 ways to handle this.
# Redraw the panel when the screen is scrolled to compensate for it.
# Use rupture technique, the panel is in a different part of RAM and will not be affected by the scroll.

This following is an incomplete list of games using hardware scrolling. From this list it can be seen that hardware scrolling has been used from 1984 :

{| class="FCK__ShowTableBorders"
|-
| ''Title''
| ''Year''
| ''Vertical''
| ''Horizontal''
| ''R3''
| ''R5''
| ''Confirmed''
|-
| [[3D Stunt Rider]]
| 1985
| No
| Yes
| No
| No
| Yes
|-
| [[Action Force]]
| 1988
| No
| Yes
| No
| No
| Yes
|-
| [[The Amazing Shrinking Man|Amazing Shrinking Man (The)]]
| 1986
| Yes
| Yes
| No
| No
| Yes
|-
| [[Anarchy]]
| 1988
| No
| Yes
| No
| No
|-
| [[Axys: The Last Battle]]
| 1991
| Yes
| No
| No
| Yes
| Yes
|-
| [[BMX Kidz]]
| 1988
| No
| Yes
| No
| No
| Yes
|-
| [[Bob Morane Science Fiction]]
| 1987
| Yes
| Yes
| No
| No
|-
| [[Boulder Dash]]
| 1984
| Yes
| Yes
| No
| No
| Yes
|-
| [[Builderland]]
| 1991
| No
| Yes
| No
| No
|-
| [[Canadair]]
| 1987
| No
| Yes
| No
| No
| Yes
|-

| [[Cessna Over Moscow]]
| 1987
| No
| Yes
| No
| No
| Yes
|-

| [[Cyborgs]]
| 1991
| Yes
| Yes
| Yes
| Yes
| Yes
|-
| [[DJ Puff's Volcanic Eruption]]
| 1992
| Yes
| Yes
| No
| No
| No
|-
| [[Doctor Who and the Mines of Terror]]
| 1986
| Yes
| Yes
| No
| No
| Yes
|-
| [[Edge Grinder]]
| 2011
| No
| Yes
| Yes
| No
| Yes
|-
| [[Energy Warrior]]
| 1987
| No
| Yes
| No
| No
| Yes
|-
| [[FlySpy]]
| 1986
| Yes
| Yes
| No
| No
|-
| [[Fusion 2]]
| 1988
| No
| Yes
| No
| No
| Yes
|-
| [[Glen Hoddle Soccer]]
| 1985
| No
| Yes
| No
| No
| Yes
|-
| [[Gothic]]
| 1988
| Yes
| Yes
| No
| Yes
|-
| [[Ghosts 'n' Goblins]]
| 1986
| No
| Yes
| Yes
| No
| Yes
|-
| [[Ghouls 'n' Ghosts]]
| 1989
| No
| Yes
| No
| No
| Yes
|-
| [[Into The Eagle's Nest]]
| 1987
| Yes
| Yes
| No
| No
| Yes
|-
| [[Jinks]]
| 1988
| No
| Yes
| Yes
| No
| Yes
|-
| [[Killer Cobra]]
| 1987
| No
| Yes
| Yes
| No
| Yes
|-
| [[Led Storm]]
| 1988
| Yes
| No
| No
| Yes
| Yes
|-
| [[Legend of Kage]]
| 1986
| Yes
| Yes
| Yes
| Yes
| Yes
|-
| [[Leviathan]]
| 1987
| Diagonal
| scroll!
| No
| No
| Yes
|-
| [[Le 5eme Axe]]
| 1985
| Yes
| Yes
| No
| No
| Yes
|-
| [[Mission Genocide]]
| 1987
| Yes
| No
| No
| Yes
| Yes
|-
| [[Monty Python's Flying Circus]]
| 1990
| Yes
| Yes
| No
| No
| Yes
|-
| [[Octoplex]]
| 1989
| Yes
| Yes
| No
| Yes(?)
| Yes
|-
| [[Out of This World]]
| 1987
| No
| Yes
| Yes
| No
| Yes
|-
| [[Paraplane]]
| 1992
| Yes
| Yes
| No
| No
|-
| [[Plate-Forme]]
| 1988
| No
| Yes
| No
| No
| Yes
|-
| [[Prehistorik 2]]
| 1992
| Yes
| Yes
| Yes
| Yes
| Yes
|-
| [[Profanation]]
| 1987
| Yes
| Yes
| Yes
| Yes
| Yes
|-
| [[Prohibition]]
| 1987
| Yes
| Yes
| No
| No
| Yes
|-
| [[Rastan]]
| 1987
| Yes
| Yes
| No
| No
| Yes
|-
| [[Realm!]]
| 1987
| Yes
| Yes
| No
| No
|-
| [[Rick Dangerous 2]]
| 1990
| No
| Yes
| No
| No
|-
| [[Rig Attack]]
| 1985
| No
| Yes
| No
| No
| Yes
|-
| [[Rockford]]
| 1988
| Yes
| Yes
| No
| No
| Yes
|-
| [[Roland on the Ropes]]
| 1984
| Yes
| Yes
| No
| No
|-
| [[The Sentinel|Sentinel (The)]]
| 1987
| Yes
| Yes
| No
| No
| Yes
|-

| [[Star Sabre]]
| 2007
| No
| Yes
| No
| No
| Yes
|-
| [[The Return of the Jedi|Return of the Jedi (The)]]
| 1989
| Diagonal
| scroll!
| No
| No
| Yes
|-
| [[Thing on a Spring]]
| 1986
| No
| Yes
| Yes
| No
| Yes
|-
| [[Skate Ball]]
| 1989
| No
| Yes
| No
| No
| Yes
|-
| [[Skateboard Kidz]]
| 1988
| Yes
| No
| No
| Yes
| Yes
|-
| [[Skate Rock]]
| 1987
| No
| Yes
| No
| No
| Yes
|-
| [[Skate Wars]]
| 1990
| No
| Yes
| No
| Yes
| Yes
|-
| [[Sly Spy Secret Agent]]
| 1990
| Yes
| Yes
| No
| No
| Yes
|-
| [[Star Avenger]]
| 1984
| No
| Yes
| No
| No
|-
| [[Star Sabre]]
| 2007
| No
| Yes
| No
| Yes
| Yes
|-
| [[Street Machine]]
| 1986
| Yes
| Yes
| No
| No
| Yes
|-
| [[Striker in the Crypts of Trogan]]
| 1992
| Yes
| Yes
| No
| No
|-
| [[Super Cauldron]]
| 1992
| Yes
| Yes
| Yes
| Yes
| Yes
|-
| [[Titan]]
| 1988
| Yes
| Yes
| No
| No
|-
| [[T.L.L. - Tornado Low Level|Tornado Low Level]]
| 1985
| Yes
| Yes
| No
| No
| Yes
|-
| [[Top Level]]
|
| Yes
| No
| No
| No
|-

| [[Twin World]]
| 1990
| Yes
| No
| No
| No
| Yes
|-

| [[Ultima Ratio]]
| 1987
| Yes
| No
| No
| No
| Yes
|-
| [[Unitrax]]
| 1987
| Yes
| Yes
| No
| No
| Yes
|-
| [[Vector Ball]]
| 1988
| Diagonal
| scroll!
| No
| No
| Yes
|-
| [[Vikings (The)]]
| 1986
| Yes
| Yes
| No
| No
| Yes
|-
| [[Warhawk]]
| 1987
| Yes
| No
| No
| Yes
| Yes
|-
| [[Wonderboy]]
| 1987
| No
| Yes
| No
| No
| Yes
|-
| [[Xeno]]
| 1986
| No
| Yes
| No
| No
| Yes
|}

=== Rupture (or splitscreen) ===

A CRTC programming technique used to split the screen into more than one block vertically.

The sizes of each block are defined using CRTC register R4. Vsync is turned off in all but one block (by setting CRTC R7 to a value larger than R4).
The start address of each block can be changed using CRTC registers R12 and R13.

This allows each block to reference different ram or to hardware scroll one block while another is static.

This method requires careful timing for the CRTC register updates, it also needs testing on all CRTC because there are differences of when each will accept and use the values programmed. However, the result can be made to work on all with more simple ruptures. Care must also be taken to ensure the timings are setup for a 50Hz screen.

It is worth noting that some monitors are more tolerant to longer or shorter frames so the result may appear correctly on them and not on others.
In addition some games may have been programmed and tested on only 1 CRTC type so may not work on others.

Wonderboy sets R4 every frame to the same value - reason unknown. But it doesn't use Rupture, because if this code is removed it works fine.

This is a an incomplete list of games that use this technique, but according to this list the earliest games used this technique was 1987:

{| class="FCK__ShowTableBorders"
|-
| ''Title''
| ''Year''
| ''Confirmed''
|-
| [[007 The Living Daylights|007 The Living Daylights]]
| 1987
| Yes
|-
| [[Action Force|Action Force]]
| 1988
| Yes
|-
| [[Axys: The Last Battle|Axys]]
| 1991
| Yes
|-
| [[Dynamic Duo|Dynamic Duo]]
| 1988
|
|-
| [[DJ Puff's Volcanic Eruption]]
| 1992
| Yes
|-
| [[Energy Warrior|Energy Warrior]]
| 1987
| Yes
|-
| [[Enlightenment: Druid 2|Enlightenment: Druid 2]]
| 1988
|
|-
| [[European 5-A-Side]]
| 1988
|
|-
| [[F1 Tornado Simulator]]
| 1991
| No
|-
| [[Grell and Falla|Grell and Falla]]
| 1992
|
|-
| [[Mission Genocide|Mission Genocide]]
| 1987
| Yes
|-
| [[Octoplex|Octoplex]]
| 1989
| Yes
|-
| [[Para Academy]]
| 1990
| No
|-
| [[Prehistorik 2|Prehistorik 2]]
| 1992
| Yes
|-
| [[Q10 Tank Buster]]
| 1991
| Yes
|-
| [[Rastan]]
| 1987
| Yes
|-
| [[Rockford]]
| 1988
| Yes
|-
| [[Santa's Christmas Capers]]
| 1990
| Yes
|-
| [[Skate Ball|Skate Ball]]
| 1989
| Yes
|-
| [[Skatewars|Skatewars]]
| 1989
|
|-
| [[Skateboard Kidz|Skateboard Kidz]]
| 1988
| Yes
|-
| [[Snowstrike|Snowstrike]]
| 1990
|
|-
| [[Storm Warrior|Storm Warrior]]
| 1989
| Yes
|-
| [[Super Cauldron|Super Cauldron]]
| 1992
| Yes
|-
| [[Turrican|Turrican]]
| 1990
| Yes
|-

| [[Twin World (Ubi Soft)|Twin World (Ubi Soft)]]
| 1990
| Yes
|-
| [[Usagi Yojimbo|Usagi Yojimbo]]
| 1988
| Yes
|-
| [[Warhawk|Warhawk]]
| 1987
| Yes
|-
| [[Xyphoes Fantasy|Xyphoes Fantasy]]
| 1991
| Yes
|-
|}

==Firmware==

The following games are known to use firmware functions. This probably explains why they are poor. If the programmer had used the hardware directly they would have lots more cycles free which they could have used to make the game better.

This list is not exhaustive.

*[[Xevious]]

[[Category:Programming]]

Programming methods used in games

2023-04-20T07:00:25Z

Esesci: /* Sampled Sound */ Add Ghost Hunters and Advanced Pinball Simulator

This section describes specific programming methods which are used in games and the games that use them.

=== Sampled Sound ===

Sampled music:
* Prehistorik 2
* Xyphoes Fantasy

The sampled speech is often stored as 4-bit values with 2 values packed into each byte. Each value is sent to one of the AY volume registers at a fixed rate.

Sampled speech:
* Chase HQ
* Bad Dudes vs Dragon Ninja
* Robocop
* Ghost Hunters
* Advanced Pinball Simulator

=== Rasters ===

[[Rasters]] is a colour changing effect.

Examples:

Zynaps.

=== Hardware Double Buffer ===

Most good CPC games use the hardware double buffer technique in order to display sprites and/or to scroll the play area smoothly.

In particular, two memory areas (instead of one) are reserved for the screen ram.

In each frame, one of the two screens is displayed while the other is not visible but is drawn to. After the draw is done, the screens are exchanged using the hardware, so that the previously invisible one is now visible and the previously visible one is invisible.

The exchange is done using the hardware specifically by changing the screen-offset, Reg 12 and 13 of the [[CRTC|CRTC]]).

This process is repeated.

The big advantage of this technique is that we can use a whole frame (or more) machine-time for our code (with no problems that arise when we alter screen ram at the same time the electron beam displays it on the monitor such as tearing or flickering).

However, page flipping eats up a lot of memory area (which is crucial especially for 64Kb machines). This explains why a lot of games can have small game-areas !

For example:
Pac-Man Emulator

=== Scrolling ===

The following types of scroll are used:

1. The player controls a character on the screen. When the character is moved the screen scrolls but the character remains in the same position on the screen. If they get to the edge of the map, they may walk up to the sides of the screen. If they walk back the other way when they reach a particular point on the screen it starts to scroll again and they remain in the same position.

2. The player controls a character on the screen. When the character is moved towards the edges of the screen, the scroll moves a whole screen in width or height. The character is now on the opposite side. e.g. the character moves left, the screen scrolls by a whole screen width, the character is now on the right. The screen only scrolls when they get close to the sides.

3. The screen always scrolls. The player controls a character who is either static or moves freely around the screen.

=== Parallax/Multi Layer Scroll===

Parallax or Multi Layer Scroll is an effect where there are 2 layers of tiles which scroll, one has priority over the other and often they move at different scroll rates.

For example, the following games have parallax or multi layer scroll:

* Wizard Willy
* Teenage Mutant Hero Turtles
* Astro Marine Corps (AMC)
* Turrican I and II
* Shadow Dancer

==== Software Scrolling ====

The screen is scrolled using the CPU only. This can be done by moving the data on the screen, or re-drawing it in a different position to give the illusion of scrolling.

Examples:

* Robocop
* Batman the Movie.

==== Hardware Scrolling ====

Hardware scrolling is performed by changing the CRTC registers R12 and R13 to define the start address of the screen. The display is automatically wrapped at 16K, so continuous incrementation of these values will scroll the screen and wrap around. The code must then update the display for new graphics.

The scrolling is in CRTC character sizes.
* 1 CRTC char horizontally is 2 bytes of RAM at a time which corresponds to 4 mode 0 pixels, 8 mode 1 pixels or 16 mode 2 pixels.
* The height of a CRTC char is defined by CRTC Register 9 (Max Raster), which is normally set to 7. Resulting in 8 scanlines per character.

Horizontal scrolling can be made smoother by using R3 (Hsync Width), in addition to using R12 and R13 and makes the scrolling effectively half a CRTC char (therefore 2 mode 0 pixels, 4 mode 1 pixels or 8 mode 2 pixels). This can be done by changing the HSYNC width values between 5 and 6. The movement is an effect of how the monitor handles the HSYNC. This effect works well on Amstrad monitors, doesn't work on modern TFT screens and produces a black and white image on a MP-2 modulator because of the adjusted HSYNC timing.

Vertical scrolling can be made smoother by using R5 (Vertical Adjust). This works on all monitors.

More recent games (e.g. Prehistorik 2, Super Cauldron) use the rupture technique when doing vertical scroll to ensure the display is a constant number of scan lines in height, and so the refresh rate is always the same.

Older games adjust R5 and don't use rupture (e.g. LED Storm, Legend of Kage), the time for a frame therefore varies by up to 7 extra scan-lines. This means the VSYNC to the monitor also varies in position by up to 7 extra scan-lines, and the stability of the image is then dependent on how the monitor handles the VSYNC.

If the game uses a status panel, there are 2 ways to handle this.
# Redraw the panel when the screen is scrolled to compensate for it.
# Use rupture technique, the panel is in a different part of RAM and will not be affected by the scroll.

This following is an incomplete list of games using hardware scrolling. From this list it can be seen that hardware scrolling has been used from 1984 :

{| class="FCK__ShowTableBorders"
|-
| ''Title''
| ''Year''
| ''Vertical''
| ''Horizontal''
| ''R3''
| ''R5''
| ''Confirmed''
|-
| [[3D Stunt Rider]]
| 1985
| No
| Yes
| No
| No
| Yes
|-
| [[Action Force]]
| 1988
| No
| Yes
| No
| No
| Yes
|-
| [[The Amazing Shrinking Man|Amazing Shrinking Man (The)]]
| 1986
| Yes
| Yes
| No
| No
| Yes
|-
| [[Anarchy]]
| 1988
| No
| Yes
| No
| No
|-
| [[Axys: The Last Battle]]
| 1991
| Yes
| No
| No
| Yes
| Yes
|-
| [[BMX Kidz]]
| 1988
| No
| Yes
| No
| No
| Yes
|-
| [[Bob Morane Science Fiction]]
| 1987
| Yes
| Yes
| No
| No
|-
| [[Boulder Dash]]
| 1984
| Yes
| Yes
| No
| No
| Yes
|-
| [[Builderland]]
| 1991
| No
| Yes
| No
| No
|-
| [[Canadair]]
| 1987
| No
| Yes
| No
| No
| Yes
|-

| [[Cessna Over Moscow]]
| 1987
| No
| Yes
| No
| No
| Yes
|-

| [[Cyborgs]]
| 1991
| Yes
| Yes
| Yes
| Yes
| Yes
|-
| [[DJ Puff's Volcanic Eruption]]
| 1992
| Yes
| Yes
| No
| No
| No
|-
| [[Doctor Who and the Mines of Terror]]
| 1986
| Yes
| Yes
| No
| No
| Yes
|-
| [[Edge Grinder]]
| 2011
| No
| Yes
| Yes
| No
| Yes
|-
| [[Energy Warrior]]
| 1987
| No
| Yes
| No
| No
| Yes
|-
| [[FlySpy]]
| 1986
| Yes
| Yes
| No
| No
|-
| [[Fusion 2]]
| 1988
| No
| Yes
| No
| No
| Yes
|-
| [[Glen Hoddle Soccer]]
| 1985
| No
| Yes
| No
| No
| Yes
|-
| [[Gothic]]
| 1988
| Yes
| Yes
| No
| Yes
|-
| [[Ghosts 'n' Goblins]]
| 1986
| No
| Yes
| Yes
| No
| Yes
|-
| [[Ghouls 'n' Ghosts]]
| 1989
| No
| Yes
| No
| No
| Yes
|-
| [[Into The Eagle's Nest]]
| 1987
| Yes
| Yes
| No
| No
| Yes
|-
| [[Jinks]]
| 1988
| No
| Yes
| Yes
| No
| Yes
|-
| [[Killer Cobra]]
| 1987
| No
| Yes
| Yes
| No
| Yes
|-
| [[Led Storm]]
| 1988
| Yes
| No
| No
| Yes
| Yes
|-
| [[Legend of Kage]]
| 1986
| Yes
| Yes
| Yes
| Yes
| Yes
|-
| [[Leviathan]]
| 1987
| Diagonal
| scroll!
| No
| No
| Yes
|-
| [[Le 5eme Axe]]
| 1985
| Yes
| Yes
| No
| No
| Yes
|-
| [[Mission Genocide]]
| 1987
| Yes
| No
| No
| Yes
| Yes
|-
| [[Monty Python's Flying Circus]]
| 1990
| Yes
| Yes
| No
| No
| Yes
|-
| [[Octoplex]]
| 1989
| Yes
| Yes
| No
| Yes(?)
| Yes
|-
| [[Out of This World]]
| 1987
| No
| Yes
| Yes
| No
| Yes
|-
| [[Paraplane]]
| 1992
| Yes
| Yes
| No
| No
|-
| [[Plate-Forme]]
| 1988
| No
| Yes
| No
| No
| Yes
|-
| [[Prehistorik 2]]
| 1992
| Yes
| Yes
| Yes
| Yes
| Yes
|-
| [[Profanation]]
| 1987
| Yes
| Yes
| Yes
| Yes
| Yes
|-
| [[Prohibition]]
| 1987
| Yes
| Yes
| No
| No
| Yes
|-
| [[Rastan]]
| 1987
| Yes
| Yes
| No
| No
| Yes
|-
| [[Realm!]]
| 1987
| Yes
| Yes
| No
| No
|-
| [[Rick Dangerous 2]]
| 1990
| No
| Yes
| No
| No
|-
| [[Rig Attack]]
| 1985
| No
| Yes
| No
| No
| Yes
|-
| [[Rockford]]
| 1988
| Yes
| Yes
| No
| No
| Yes
|-
| [[Roland on the Ropes]]
| 1984
| Yes
| Yes
| No
| No
|-
| [[The Sentinel|Sentinel (The)]]
| 1987
| Yes
| Yes
| No
| No
| Yes
|-

| [[Star Sabre]]
| 2007
| No
| Yes
| No
| No
| Yes
|-
| [[The Return of the Jedi|Return of the Jedi (The)]]
| 1989
| Diagonal
| scroll!
| No
| No
| Yes
|-
| [[Thing on a Spring]]
| 1986
| No
| Yes
| Yes
| No
| Yes
|-
| [[Skate Ball]]
| 1989
| No
| Yes
| No
| No
| Yes
|-
| [[Skateboard Kidz]]
| 1988
| Yes
| No
| No
| Yes
| Yes
|-
| [[Skate Rock]]
| 1987
| No
| Yes
| No
| No
| Yes
|-
| [[Skate Wars]]
| 1990
| No
| Yes
| No
| Yes
| Yes
|-
| [[Sly Spy Secret Agent]]
| 1990
| Yes
| Yes
| No
| No
| Yes
|-
| [[Star Avenger]]
| 1984
| No
| Yes
| No
| No
|-
| [[Star Sabre]]
| 2007
| No
| Yes
| No
| Yes
| Yes
|-
| [[Street Machine]]
| 1986
| Yes
| Yes
| No
| No
| Yes
|-
| [[Striker in the Crypts of Trogan]]
| 1992
| Yes
| Yes
| No
| No
|-
| [[Super Cauldron]]
| 1992
| Yes
| Yes
| Yes
| Yes
| Yes
|-
| [[Titan]]
| 1988
| Yes
| Yes
| No
| No
|-
| [[T.L.L. - Tornado Low Level|Tornado Low Level]]
| 1985
| Yes
| Yes
| No
| No
| Yes
|-
| [[Top Level]]
|
| Yes
| No
| No
| No
|-

| [[Twin World]]
| 1990
| Yes
| No
| No
| No
| Yes
|-

| [[Ultima Ratio]]
| 1987
| Yes
| No
| No
| No
| Yes
|-
| [[Unitrax]]
| 1987
| Yes
| Yes
| No
| No
| Yes
|-
| [[Vector Ball]]
| 1988
| Diagonal
| scroll!
| No
| No
| Yes
|-
| [[Vikings (The)]]
| 1986
| Yes
| Yes
| No
| No
| Yes
|-
| [[Warhawk]]
| 1987
| Yes
| No
| No
| Yes
| Yes
|-
| [[Wonderboy]]
| 1987
| No
| Yes
| No
| No
| Yes
|-
| [[Xeno]]
| 1986
| No
| Yes
| No
| No
| Yes
|}

=== Rupture (or splitscreen) ===

A CRTC programming technique used to split the screen into more than one block vertically.

The sizes of each block are defined using CRTC register R4. Vsync is turned off in all but one block (by setting CRTC R7 to a value larger than R4).
The start address of each block can be changed using CRTC registers R12 and R13.

This allows each block to reference different ram or to hardware scroll one block while another is static.

This method requires careful timing for the CRTC register updates, it also needs testing on all CRTC because there are differences of when each will accept and use the values programmed. However, the result can be made to work on all with more simple ruptures. Care must also be taken to ensure the timings are setup for a 50Hz screen.

It is worth noting that some monitors are more tolerant to longer or shorter frames so the result may appear correctly on them and not on others.
In addition some games may have been programmed and tested on only 1 CRTC type so may not work on others.

Wonderboy sets R4 every frame to the same value - reason unknown. But it doesn't use Rupture, because if this code is removed it works fine.

This is a an incomplete list of games that use this technique, but according to this list the earliest games used this technique was 1987:

{| class="FCK__ShowTableBorders"
|-
| ''Title''
| ''Year''
| ''Confirmed''
|-
| [[007 The Living Daylights|007 The Living Daylights]]
| 1987
| Yes
|-
| [[Action Force|Action Force]]
| 1988
| Yes
|-
| [[Axys: The Last Battle|Axys]]
| 1991
| Yes
|-
| [[Dynamic Duo|Dynamic Duo]]
| 1988
|
|-
| [[DJ Puff's Volcanic Eruption]]
| 1992
| Yes
|-
| [[Energy Warrior|Energy Warrior]]
| 1987
| Yes
|-
| [[Enlightenment: Druid 2|Enlightenment: Druid 2]]
| 1988
|
|-
| [[European 5-A-Side]]
| 1988
|
|-
| [[F1 Tornado Simulator]]
| 1991
| No
|-
| [[Grell and Falla|Grell and Falla]]
| 1992
|
|-
| [[Mission Genocide|Mission Genocide]]
| 1987
| Yes
|-
| [[Octoplex|Octoplex]]
| 1989
| Yes
|-
| [[Para Academy]]
| 1990
| No
|-
| [[Prehistorik 2|Prehistorik 2]]
| 1992
| Yes
|-
| [[Q10 Tank Buster]]
| 1991
| Yes
|-
| [[Rastan]]
| 1987
| Yes
|-
| [[Rockford]]
| 1988
| Yes
|-
| [[Santa's Christmas Capers]]
| 1990
| Yes
|-
| [[Skate Ball|Skate Ball]]
| 1989
| Yes
|-
| [[Skatewars|Skatewars]]
| 1989
|
|-
| [[Skateboard Kidz|Skateboard Kidz]]
| 1988
| Yes
|-
| [[Snowstrike|Snowstrike]]
| 1990
|
|-
| [[Storm Warrior|Storm Warrior]]
| 1989
| Yes
|-
| [[Super Cauldron|Super Cauldron]]
| 1992
| Yes
|-
| [[Turrican|Turrican]]
| 1990
| Yes
|-

| [[Twin World (Ubi Soft)|Twin World (Ubi Soft)]]
| 1990
| Yes
|-
| [[Usagi Yojimbo|Usagi Yojimbo]]
| 1988
| Yes
|-
| [[Warhawk|Warhawk]]
| 1987
| Yes
|-
| [[Xyphoes Fantasy|Xyphoes Fantasy]]
| 1991
| Yes
|-
|}

==Firmware==

The following games are known to use firmware functions. This probably explains why they are poor. If the programmer had used the hardware directly they would have lots more cycles free which they could have used to make the game better.

This list is not exhaustive.

*[[Xevious]]

[[Category:Programming]]

Section Jaguar

2022-09-08T23:39:50Z

Esesci:

[[Image:JAGUAR logo.GIF|right|thumb|250px|Section Jaguar's cracktro]]

Section Jaguar was one of the famous Cracker from Germany. He had the jaguar-emblem as his Logo and later used the skull in his cracktros.

Active 1988/1989 with other famouse crackers like Groo, The Frog

The graphics in their intro is an artwork from the comics [https://en.wikipedia.org/wiki/The_Saga_of_Crystar The Saga of Crystar] by Michael Golden. The same artwork is also featured in Danzig's 1988 album "Danzig".

== Known cracks ==

== Weblinks ==

[http://cpccrackers.free.fr/ CPCCrackers]

[[Category:CPC scene members]][[Category:Stub]]

Section Jaguar

2022-09-08T23:39:20Z

Esesci:

[[Image:JAGUAR logo.GIF|right|thumb|250px|Section Jaguar's cracktro]]

Section Jaguar was one of the famous Cracker from Germany. He had the jaguar-emblem as his Logo and later used the skull in his cracktros.

Active 1988/1989 with other famouse crackers like Groo, The Frog

The graphics in their intro is an artwork from the comics [https://en.wikipedia.org/wiki/The_Saga_of_Crystar The Saga of Crystar] by Michael Golden.

== Known cracks ==

== Weblinks ==

[http://cpccrackers.free.fr/ CPCCrackers]

[[Category:CPC scene members]][[Category:Stub]]

Section Jaguar

2022-09-08T23:38:44Z

Esesci:

[[Image:JAGUAR logo.GIF|right|thumb|250px|Section Jaguar's cracktro]]

Section Jaguar was one of the famous Cracker from Germany. He had the jaguar-emblem as his Logo and later used the skull in his cracktros.

Active 1988/1989 with other famouse crackers like Groo, The Frog

The graphics in their intro is an artwork from the comics [The Saga of Crystar](https://en.wikipedia.org/wiki/The_Saga_of_Crystar) by Michael Golden.

== Known cracks ==

== Weblinks ==

[http://cpccrackers.free.fr/ CPCCrackers]

[[Category:CPC scene members]][[Category:Stub]]

Disk image file format

2022-06-18T22:12:58Z

Esesci: /* Sector info */ Correct control mark bit in status register 2

[[Category:DATA Storage| ]][[Category:DSK images| ]][[Category:Emulator| ]]
'''Disk image file format'''

This document describes the standard disk image format. It has the file extension ".DSK".

== Disc Information block ==

The "Disc Information block" is always at offset 0 in the disk image file. If track data exists, then this will immediatly follow the Disc Information Block and will start at offset &100 in the disc image file.

The "Disc Information block" has the following structure:

{|{{Prettytable|width: 700px; font-size: 2em;}}
|''offset''||''description''||''bytes''
|-
|00-21||"MV - CPCEMU Disk-File\r\nDisk-Info\r\n"||34
|-
|22-2f||name of creator||14
|-
|30||number of tracks||1
|-
|31||number of sides||1
|-
|32-33||size of a track (little endian; low byte followed by high byte)||2
|-
|34-ff||not used (0)||204
|}

Notes:

* Track 0 (or Track 0 side 0 for double sided disks) immediatly follows the Disk Information Block, and is at offset &100 in the disk image.

* "MV - CPC" must be present, because it is used to identify the file as a disk image. It is sufficient to check this to identify the file as being a disk image.
* "\r" is the C programming language equivalent of ASCII character 13.
* "\n" is the C programming language equivalent of ASCII character 10.
* '''All''' tracks must be the same size.
* "size of track" is used to calculate the location of the data for a chosen track.
* "size of track" includes the &100 byte Track Information Block.
* '''All''' tracks must have a "Track Information Block"
* track lengths are stored in the same order as the tracks in the image e.g. In the case of a double sided disk: Track 0 side 0, Track 0 side 1, Track 1 side 0 etc...
* The track blocks are stored in increasing order 0..number of tracks, with alternating sides interleaved if the disc image describes a double sided disk. e.g. if the disk image represents a double sided disk, the order of tracks is: track 0 side 0, track 0 side 1, track 1 side 0, track 1 side 1.... track (number of tracks-1) side 0, track (number of tracks-1) side 1

The tracks are always ordered in this way regardless of the disc-format described by the disc image.

* A standard disk image can be used to describe a copy-protected disk, but will often result in a file which is larger than the same disk described by a extended disk image. For a standard disk image to represent a copy-protected disk:
** All track sizes in the standard disk image must be the same. This value therefore would be the size of the largest track, and other tracks would have unused space in them.
** All sector sizes within each track must be the same size, but not necessarily the same size as the sectors for another track. If a track contained different sized sectors, the size of the largest sector should be used. This would result in some wasted space.

== Track Information Block ==

Each Track Block comprises a Track Information Block and sector data. The sector data is always at an offset of &100 bytes from the start of the track block. The data for the next track in the disc image immediatly follows the data for the current track.

The first Track Block is located at offset &100 in the disk image file. The track block starts with the Track Information Block and has this form.

{|{{Prettytable|width: 700px; font-size: 2em;}}
|''offset''||''description''||''bytes''
|-
|00 - 0c||"Track-Info\r\n"||13
|-
|0d - 0f||unused||3
|-
|10||track number||1
|-
|11||side number||1
|-
|12 - 13||unused||2
|-
|14||sector size||1
|-
|15||number of sectors||1
|-
|16||GAP#3 length||1
|-
|17||filler byte||1
|-
|18 - xx||Sector Information List||xx
|}

'''Notes:'''

* "number of sectors" is used to identify the number of valid entries in the sector information list.
* "sector size" parameter is used to calculate the location of each sector's data. Therefore, The data allocated for each sector must be the same.

If the track contains different sized sectors, then the data allocated must be the size of the biggest sector. The "sector size" parameter is used to calculate the location of the sector data.

* Sector data always follows Track Information Block at offset &100 from the start of the track information block.
* Sector data is stored in the same order as the sectors in the sector info block.

== Sector info ==

{|{{Prettytable|width: 700px; font-size: 2em;}}
|''offset''||''description''||''bytes''
|-
|00||track (equivalent to C parameter in NEC765 commands)||1
|-
|01||side (equivalent to H parameter in NEC765 commands)||1
|-
|02||sector ID (equivalent to R parameter in NEC765 commands)||1
|-
|03||sector size (equivalent to N parameter in NEC765 commands)||1
|-
|04||FDC status register 1 (equivalent to NEC765 ST1 status register)||1
|-
|05||FDC status register 2 (equivalent to NEC765 ST2 status register)||1
|-
|06-07||notused (0)||2
|}

'''Notes:'''

* The following bits are used from NEC765 status register 1:
** b7 EN (End of Cylinder)
** b5 DE (Data Error)
** b2 ND (No Data)
** b0 MA (Missing Address Mark)
* The following bits are used from NEC765 status register 2:
** b6 CM (Control Mark)
** b5 DD (Data Error in Data field)
** b0 MD (Missing address Mark in Data field)
* For 8k Sectors (N="6"), only 1800h bytes is stored.

== General format ==

=== Single sided DSK images ===

* Disc Information Block
* Track 0 data
** Track Information Block
** Sector data
* Track 1 data
** Track Information Block
** Sector data

. . . .

* Track (number_of_tracks-1) data
** Track Information Block
** Sector data

=== Double sided DSK images ===

* Disc Information Block
* Track 0 side 0 data
** Track Information Block
** Sector data
* Track 0 side 1 data
** Track Information Block
** Sector data

. . . .

* Track (number_of_tracks-1) side 1 data
** Track Information Block
** Sector data

AMSDOS Header

2021-01-13T02:49:03Z

Esesci: Fix errors

In [[AMSDOS]] it is possible to store files in two ways: headerless and with a header. Headerless files are often files which were created with [[OPENOUT]] and ''SAVE"filename",a''. Programs normally have a file header, which consist of 128 bytes and contain the following data:

{| class="wikitable"
|-
! Size !! Name !! Notes
|-
| BYTE || User number || 0-15, or #E5 for deleted entries
|-
| 8 BYTES || Filename || Unused characters are filled with space
|-
| 3 BYTES || Extension || Unused characters are filled with space
|-
| DWORD || Zero || Contains all zeroes
|-
| BYTE || Block number || Tape only
|-
| BYTE || Last block || Tape only
|-
| BYTE || File type || 0:BASIC 1:Protected 2:Binary (ASCII files don't have headers but a fake header is built in memory with the file type #16, "Unprotected ASCII v1")
|-
| WORD || Data location || Address of the 2KB buffer
|-
| WORD ||Load address ||
|-
| BYTE || First block || Set to #FF, only used for output files
|-
| WORD ||style="white-space: nowrap;"| Logical length || Actual file length is here
|-
| WORD || Entry address ||
|-
| 36 BYTES || Unused ||
|-
| 3 BYTES || Real length || 24-bit number. Just a copy, not used!
|-
| WORD || Checksum || Unsigned sum of all bytes until this field
|-
|style="white-space: nowrap;"|59 BYTES || Unused || Free to use
|}

To calculate the checksum just add all bytes from 00 up to and including byte 66 together.

This is only a summary. All details are in [[Firmware Guide]] chapter 9, page 4.

[[Category:Disc Operating System]]
[[Category:Programming]]

AMSDOS Header

2021-01-13T02:40:10Z

Esesci:

In [[AMSDOS]] it is possible to store files in two ways: headerless and with a header. Headerless files are often files which were created with [[OPENOUT]] and ''SAVE"filename",a''. Programs normally have a file header, which consist of 128 bytes and contain the following data:

{| class="wikitable"
|-
! Size !! Name !! Notes
|-
| BYTE || User number || 0-15, or #E5 for deleted entries
|-
| 8 BYTES || Filename || Unused characters are filled with space
|-
| 3 BYTES || Extension || Unused characters are filled with space
|-
| BYTE || Block number || Tape only
|-
| BYTE || Last block || Tape only
|-
| BYTE || File type || 0:BASIC 1:Protected 2:Binary (ASCII files don't have headers)
|-
| WORD || Data length || ???
|-
| WORD || Load address ||
|-
| BYTE || First block || Tape only?
|-
| WORD || Logical length || Actual file length is here
|-
| WORD || Entry address ||
|-
| 36 BYTES || Unused ||
|-
| 3 BYTES || Real length || 24-bit number. Just a copy, not used!
|-
| WORD || Checksum || Unsigned sum of all bytes until this field
|-
| 59 BYTES || Unused || Free to use
|}

To calculate the checksum just add all bytes from 00 up to and including byte 66 together.

This is only a summary. All details are in [[Firmware Guide]] chapter 9, page 4.

[[Category:Disc Operating System]]
[[Category:Programming]]

AMSDOS Header

2021-01-13T02:39:24Z

Esesci: Update summary to a table

In [[AMSDOS]] it is possible to store files in two ways: headerless and with a header. Headerless files are often files which were created with [[OPENOUT]] and ''SAVE"filename",a''. Programs normally have a file header, which consist of 128 bytes and contain the following data:

{| class="wikitable"
|-
! Size !! Name !! Notes
|-
| BYTE || User number || 0-15, or #E5 for deleted entries
|-
| 8 BYTES || Filename || Unused characters are filled with space
|-
| 3 BYTES || Extension || Unused characters are filled with space
|-
| BYTE || Block number || Tape only
|-
| BYTE || Last block || Tape only
|-
| BYTE || File type || 0:BASIC 1:Protected 2:Binary (ASCII files don't have headers)
|-
| WORD || Length || ???
|-
| WORD || Load address ||
|-
| BYTE || First block || Tape only?
|-
| WORD || Logical length || Actual file length is here
|-
| WORD || Entry address ||
|-
| 36 BYTES || Unused ||
|-
| 3 BYTES || Real length || 24-bit number. Just a copy, not used!
|-
| WORD || Checksum || Unsigned sum of all bytes until this field
|-
| 59 BYTES || Unused || Free to use
|}

To calculate the checksum just add all bytes from 00 up to and including byte 66 together.

This is only a summary. All details are in [[Firmware Guide]] chapter 9, page 4.

[[Category:Disc Operating System]]
[[Category:Programming]]

CPC old generation

2019-02-22T00:52:53Z

Esesci: /* Hardware description */ use mirror of the dead link

[[Category:Hardware|*]][[Category:CPC Internal Components| ]][[Category:CPC History|*]][[Category:Amstrad Products| ]]

[[Image:464.png|thumb|CPC 464 with Colour monitor]]
[[Image:Schneider 664 en.jpg|thumb|German CPC 664]]

''The following text was copied in part from the [http://en.wikipedia.org/wiki/Amstrad_CPC English Wikipedia article].''

==Hardware description==
All CPC models were based on a [[Zilog]] [[Z80]] processor clocked at 4 MHz. Because a common pool of RAM is shared with the video circuits, the Z80 may only make a memory access once every four cycles, which has the effect of rounding all instruction cycle lengths up to the next multiple of four. For details, see [https://web.archive.org/web/20170324233713/http://www.grimware.org/doku.php/documentations/devices/z80 a nearly complete list of instructions with timings (number of cycles) for each.]

The system came with 64 KB or 128 KB of RAM depending on the model (capable of being expanded to more). The machines also featured a standard 9-pin Atari-style joystick socket which was able to take two joysticks via a splitter.

The machines' dimensions are:
*'''CPC464''' : 17 x 57.5 x 7.5
*'''CPC6128''' : 17.5 x 51.1 x 5

===Video (graphics): modes, outputs===
Underlying the CPC's video output was the [[CRTC|Motorola 6845]] address generator. This chip was connected to a pixel generator that supported 4 bpp, 2 bpp and 1 bpp output (bits per pixel). The address generator was clocked at a constant rate so the 4 bpp display generated half as many pixels as the 2 bpp and a quarter as many as the 1 bpp.

The ROM featured three built-in display resolutions but many others could be achieved by reprogramming the 6845.

The standard [[video modes]] were:
*'''Mode 0''': '''160×200''' pixels with 16 colours (4 bpp)
*'''Mode 1''': '''320×200''' pixels with 4 colours (2 bpp)
*'''Mode 2''': '''640×200''' pixels with 2 colours (1 bpp)
*'''Mode 3''': '''160×200''' pixels with 4 colours (2 bpp) (this is not an official mode, but rather a side-effect of the hardware)

A colour palette of 27 colours was supported, derived from RGB colour space with each component assigned as either off, half on or on. The later '''Plus''' models extended this to 4096 colours and added support for hardware sprites.

This hardware compares well with the other 8-bit computers. In particular the CPC lacks the colour clash of the ZX Spectrum, and clever programming of the 6845 could produce overscan, different resolutions (although with the same pixel density) and smooth pixel scrolling.

The machine lacked either a RF TV or composite video output and instead shipped with a proprietary 5-pin DIN connector intended for use solely with the supplied Amstrad monitor. An external adapter for RF TV was available to be bought separately.

The five-pin DIN connector is capable of driving a television with a correctly wired SCART lead.

===Audio (sound)===
The CPC used the General Instrument AY-3-8912 sound chip, providing three channels, each configurable to generate square waves, white noise or both. A small array of hardware volume envelopes are available.

Output was provided in mono by a small (4 cm) built-in loudspeaker with volume control, driven by an unusually powerful amplifier. Stereo output was provided through a 3.5mm headphone jack, not present on some early CPC464 models. In those models, what looked like a standard 3.5" headphone jack was actually used for connecting an external tape recorder, although later models used a five-pin DIN connector for the same purpose.

Playback of digital sound samples at a resolution of a little better than 5-bit, as heard on the title screen of the game ''RoboCop'', was possible through clever programming of the sound chip. This trick was very processor intensive and hard to combine with any other processing.

===The 3" floppy disk drives===
Amstrad's idiosyncratic choice of Hitachi's 3" floppy disk drive, when the rest of the PC industry was moving to Sony's 3.5" format, is often claimed to be due to Amstrad bulk-buying a large consignment of 3" drive units in Asia. The cheapest drive (built-in in later models) was a single-sided 40-track unit that required the user to physically remove and flip the disk to access both sides. Each side had its own independent write-protect switch. The sides were termed "A" and "B", with each one holding 180KB (178KB in AMSDOS format) for a total of 360KB per disc.

The disk drive interface was a NEC 765 FDC, used for the same purpose in the IBM PC/XT, PC/AT and PS/2 machines. Many of its features were unused in order to cut costs, namely DMA transfers and support for single density disks. Disks were formatted as double density using Modified Frequency Modulation.

Disks were shipped in a paper sleeve or a hard plastic case resembling a compact disc "jewel" case. The casing is thicker and more rigid than that of 3.5" diskettes and the sliding metal cover to protect the media surface is internal to the casing and latched, unlike the simple external sliding cover of Sony's version (some reviews at the time reported driving over them with no problems). Because of this they were significantly more expensive than both the 5.25" and 3.5" alternatives. This, combined with their low nominal capacities and their essentially proprietary nature, lead to the format being discontinued when the CPC itself was discontinued.

Apart from Amstrad's other 3" machines, the PCW and the ZX Spectrum +3 (produced by Amstrad after their acquisition of the Spectrum from Sinclair), the only other computer systems to use them were the Sega SF-7000 and mostly obscure and exotic CP/M systems such as the Tatung Einstein and Osborne machines. It should be noted that some of these machines used drives with different pinouts and care should be taken when replacing drives.

The data formatting of 3" disks was very similar to that of 5¼" disks, and the Amstrad CPC machines were able to use 5¼" drives through their "external drive" port - either one specially designed for use by the CPC or an adapted IBM-PC drive.

A more popular alternative was to attach an adapted IBM-PC 3½" drive for operation in either single-sided 180 KB or double-sided 360 KB mode, although with the later availability of the PARADOS Disc Operating System, 720k per disc became available. (It was possible to patch CP/M Plus so that it recognised 80 track double sided disk formats, too.)

===Serial port adaptor===
An official RS-232-C D25 serial port adaptor was produced that attached to the expansion connector at the rear of the machine, and had a through-connector for the CPC464 disk drive or other peripherals. The adaptor came with a "''Book of Spells''" for facilitating data transfer between other systems using a proprietary protocol in the device's own ROM, as well as terminal software to connect to British Telecom's Prestel service. A separate version of the ROM was created for the U.S. market due to the use of the commands "SUCK" and "BLOW", which were considered unacceptable there.

===Similarities to the BBC Micro===
The CPC has been termed an "improved Z80 implementation of the (earlier) BBC Micro" due to similarities in firmware and hardware. Both used the Motorola 6845 video address generator and the two have very similar sound output chips - the General Instrument AY-3-8912 in the CPC provided three tone channels each optionally with added noise and the Texas Instruments SN76489 in the BBC offered three tone channels and one exclusive noise channel.

The BBC Micro used an Intel 8271 floppy disc controller. The CPC used the Intel 8272, which is similar to the 8271 but contains the addition of a double density (MFM) mode.

The "two cursor" BASIC editing system seen on the Amstrad CPC (whereby holding Shift and using the cursor keys moves a shadow text cursor allowing text to be copied from another area of the screen to the normal cursor) was a lift from BBC BASIC, albeit substantially improved by allowing free movement of the normal cursor.

Both systems provided similar systems of full hardware abstraction through Operating System calls. This saves programs which don't require time critical hardware access from having to touch the underlying machine and provides a level of machine portability for those programs.

As the CPC had its own dialect of [[BASIC]], namely [[Locomotive BASIC]], so the BBC Micro has its own version named [[BBC BASIC]]. BBC BASIC evolved with subsequent models of BBC computers and with Acorn's next system, the Archimedes. Both had their own sets of advantages: Locomotive BASIC was faster in many contexts, had native support for text windows, had more comprehensive commands for manipulating sound, ''etc.''; BBC BASIC had support for procedures (rather than just arithmetic functions), an inline assembler, and others. Of note is the fact that among the numerous [http://www.bbcbasic.co.uk/bbcbasic.html ports of BBC Basic] produced by the company [http://www.rtrussell.co.uk/ R.T. Russell] is a version especially adapted for the Amstrad CPC, including support for its specific graphics and sound capabilities; there is also a generic version for [[CP/M]].

==Software==
===Built-in BASIC and operating system===
Like most home computers at the time, the CPC had its OS and a BASIC interpreter built in as ROM. It used Locomotive BASIC - a variant specifically written for the CPC hardware which as a result was faster, more comfortable and more powerful than the generic but common Microsoft BASIC used by the Commodore 64 and MSX amongst others. It was particularly notable for providing easy access to the machine's video and audio resources in contrast to the arcane POKE commands required on some Microsoft implementations (the MSX implementation of Microsoft Basic being an exception, which even allowed for hardware sprite manipulation and collision detection).

===Other languages===
Although it was possible to obtain compilers for Locomotive BASIC, BCPL, C, Forth, and Turbo Pascal the majority of the CPC's software was written in native Z80 assembly language.

An interpreter for the educational language LOGO was also supplied with the 664 and 6128 (and available for the 464 with purchase of an external disc drive).

==What was in the box?==

=== CPC464 ===

* The computer itself, including built-in [[Datacorder]]
* [[Demostration tape or disc|Demonstration tape]] in local language (UK, Germany, France, Spain)
* [[User Manual]]
* Either an [[Amstrad GT64/GT65 Green Monitor|Amstrad GT64 (Later: GT65) green monitor]] or an [[Amstrad CTM640/CTM644 Color Monitor|Amstrad CTM640 (Later: CTM644) Colour Monitor]]
* Optional: [[Amstrad MP1/MP2 modulator|Amstrad MP-1 (Later: MP-2) TV modulator and power supply]]
* A Gamepack consisting of 12 Amsoft Titles on Tape.

<gallery>
Image:CPC464_pcb_r1.jpg|CPC464 PCB revision 0 (original)
Image:CPC464_pcb_r3.jpg|CPC464 PCB revision 3 (costdown)
Image:CPC464_new_amstrad_logo.jpg|CPC464 (new Amstrad logo - photo from costdown model)
</gallery>

=== CPC472 ===
The CPC 472 was a spanish version of the CPC 464 with additional (nonfunctional) 8 KB RAM. The reason for this was that Amstrad wanted to circumvent a Spanish law that levied an extra tax for machines with 64KB or less of memory; thus, they upped the spec to 72KB by including an additional 8KB though this extra memory was not functional.

* Amstrad CPC [[472]]
<gallery>
Image:CPC_472_es.jpg|The CPC472
</gallery>
=== CPC664 ===

* The computer itself, including built-in 3" disk drive
* [[System Disk]]: CP/M 2.2 disk with demo in local language (UK, Germany, France, Spain)
* [[User Manual]]
* Either an [[Amstrad GT64/GT65 Green Monitor|Amstrad GT65 green monitor]] or an [[Amstrad CTM640/CTM644 Color Monitor|Amstrad CTM644 Colour Monitor]]
* Optional: [[Amstrad MP1/MP2 modulator|Amstrad MP-2 TV modulator and power supply]]

<gallery>
Image:664.jpg|The 664 in high-res
Image:CPC664_Top.jpg|CPC 664 Top
Image:CPC664_PCB_Top.jpg|CPC 664 Motherboard Top
Image:CPC664_PCB_Bottom.jpg|CPC 664 Motherboard Bottom
</gallery>

==== Links ====

* http://www.sellmyretro.com/ - Buy new keyboard membranes for CPC664 from RWAP software
* http://www.rwapsoftware.co.uk/ - RWAP Software, makers of membranes for Sinclair, Enterprise and CPC664

=== CPC6128 ===

* The computer itself, including built-in 3" disk drive
* [[System Disk]]s with CP/M Plus, CP/M 2.2 and a demo in local language (UK, Germany, France, Spain)
* [[User Manual]]
* Either an [[Amstrad GT64/GT65 Green Monitor|Amstrad GT65 green monitor]] or an [[Amstrad CTM640/CTM644 Color Monitor|Amstrad CTM644 Colour Monitor]]
* Optional: [[Amstrad MP1/MP2 modulator|Amstrad MP-2 TV modulator and power supply]]
* Later models came with the [[Amstrad PP8 Promotional Pack]]

<gallery>
Image:CPC6128_Top.jpg|CPC 6128 Top
Image:CPC6128_PCB_Top_(Z70290_MC0020B).jpg|CPC 6128 Motherboard Top
Image:CPC6128_PCB_Bottom_(Z70290_MC0020B).jpg|CPC 6128 Motherboard Bottom
</gallery>

=== DDI-1 ===

* Controller DDI-1
* 3" disk drive FD-1
* [[System Disk]]: CP/M 2.2 disk with demo
* [[User Manual]]

==Others==

* [[Keyboard Versions]]
* [[Mainboard Versions]]
* [[CPC6128_Keyboard_Disassembled]]
*[[CPC464 & CPC664_logos | CPC Case logos]]

==Clones==

See [[Clones]] for a list of classic and modern clones.