CPCWiki - THE Amstrad CPC encyclopedia! - User contributions [en]

File:Robot PD - 13100.zip

2026-04-10T08:24:51Z

Octoate:

Ansiterm

2026-04-10T08:24:39Z

Octoate: add link to Robot PD disc 13100

Ansiterm is an ansi terminal program for Amstrad written by Paul Martin.
It was distributed on [[Robot PD]] disc 13100.

== Review ==
[[ACU_Issue_4,_1991|ACU issue 77 April 1991 (page 48 and 49)]]

<gallery caption="Amstrad Computer User, Issue 4, 1991">
Image:ACU9104-048.jpg|Page 48
Image:ACU9104-049.jpg|Page 49
</gallery>

== Downloads ==

* [[Media:Robot PD - 13100.zip|Robot PD disc 13100]]

[[Category:Communication Software]]

Ansiterm

2026-04-10T08:22:53Z

Octoate: add review pages that are already available on the CPCWiki

Schneider BTX Modul

2026-03-02T20:52:46Z

Octoate: add scans of the manual, the box and the certificate

== Description ==

Schneider BTX module for the CPC. The hardware design is based on a universal BTX decoder made by Siemens. It is connected to the CPC's expansion port and additionally hooked in between computer and monitor. The module must also be connected to a BTX modem with a D-BT 03 port. These modems were provided by the Deutsche Post and had to be returned after use, because the BTX subscriber ID was hard-coded within the device.

* Type: PC/HC-Decoder
* Country: Germany
* OEM: Siemens
* Year: 1987
* Connectors: D-BT 03, RGB for Monitor or colorprinter
* Protocol: CEPT
* ID Numbers: P07747, Siemens S30817-K732-A101-1 / A30817-X732-A100-1, Schneider Ident Nr. 36445 or 36486

== Bildschirmtext (BTX) ==

BTX (Bildschirmtext, translated as Screentext) has been a German service, allowing to transfer data via telephone line. In the 8bit era, the Deutsche Bundespost (German postal service) still owned the monopoly for telecommunications in Germany, so the only legal way to transmit electronic data via telephone line has been to use their BTX service. The service was ultimatively suspended in 2007.

Beginning in late 2019, some work has begun to revive parts of the BTX service. There are [https://btx-museum.de/2020/02/29/der-neue-dbt-03-emulator/ emulators providing D-BT 03 ports], and some BTX pages were [https://www.heise.de/newsticker/meldung/36C3-Congress-wie-1984-mit-BTX-und-Originalarchiven-4624507.html restored by feeding recordings of original modem sessions to software demodulators].

== Pictures ==

<gallery>
File:SchneiderBtxModulCPC.jpg
File:SchneiderBtxModulCPC-close.jpg
File:SchneiderBtxModulCPC36486.jpg
File:SchneiderBtxModulCPC36486-2.jpg
</gallery>

=== PCB ===

<gallery>
File:Schneider BTX Modul - top.jpg|Top
File:Schneider BTX Modul - bottom.jpg|Bottom
</gallery>

== Case ==

'''Note''': Schneider also made a BTX module for Schneider Television Sets, although that device had nothing to do with the CPC, its housing was later re-used for the CPC's [[Schneider RS232 Interface]].

== Downloads ==

* [[Media:Schneider BTX Modul ROM dump.zip|Schneider BTX module ROM dump]]
* [[Media:Schneider BTX Modul Manual (German).pdf|Manual (German)]]
* [[Media:Schneider BTX Modul Geraete-Pass.pdf|Certificate for HiFi-Systems (Geräte-Paß)]]
* [[Media:Schneider BTX Modul Box.pdf|Scan of the box]]

== Weblinks ==

* http://en.wikipedia.org/wiki/Bildschirmtext - wikipedia article on BTX (english, short description)
* http://de.wikipedia.org/wiki/Bildschirmtext - wikipedia article on BTX (german, more detailed description)
* https://btx-museum.de/2020/02/29/der-neue-dbt-03-emulator/ (german)
* https://www.heise.de/newsticker/meldung/36C3-Congress-wie-1984-mit-BTX-und-Originalarchiven-4624507.html (german)

[[Category:Network]]

File:Schneider BTX Modul Box.pdf

2026-03-02T20:52:11Z

Octoate: Scan of the box of the Schneider BTX module (Top, Bottom and Side).

Scan of the box of the Schneider BTX module (Top, Bottom and Side).

File:Schneider BTX Modul Geraete-Pass.pdf

2026-03-02T20:51:22Z

Octoate: Certificate for HiFi-Systems (in German "Geräte-Paß") of the Schneider BTX module

Certificate for HiFi-Systems (in German "Geräte-Paß") of the Schneider BTX module

File:Schneider BTX Modul Manual (German).pdf

2026-03-02T20:50:28Z

Octoate: Manual of the Schneider BTX module in German.

Manual of the Schneider BTX module in German.

File:Schneider BTX Modul ROM dump.zip

2026-02-28T23:25:48Z

Octoate: Octoate uploaded a new version of File:Schneider BTX Modul ROM dump.zip

=={{int:filedesc}}==
{{Information
|description={{en|1=This file contains the dump of the ROM of the Schneider BTX module}}
|date=2026-02-28
|source={{own}}
|author=[[User:Octoate|Octoate]]
|permission=
|other versions=
}}

=={{int:license-header}}==
{{self|cc-by-sa-4.0}}

[[Category:Uploaded with UploadWizard]]
[[Category:Hardware]]

Schneider BTX Modul

2026-02-28T19:49:03Z

Octoate: added pictures of the pcb and ROM dump of the interface

== Description ==

Schneider BTX module for the CPC. The hardware design is based on a universal BTX decoder made by Siemens. It is connected to the CPC's expansion port and additionally hooked in between computer and monitor. The module must also be connected to a BTX modem with a D-BT 03 port. These modems were provided by the Deutsche Post and had to be returned after use, because the BTX subscriber ID was hard-coded within the device.

* Type: PC/HC-Decoder
* Country: Germany
* OEM: Siemens
* Year: 1987
* Connectors: D-BT 03, RGB for Monitor or colorprinter
* Protocol: CEPT
* ID Numbers: P07747, Siemens S30817-K732-A101-1 / A30817-X732-A100-1, Schneider Ident Nr. 36445 or 36486

== Bildschirmtext (BTX) ==

BTX (Bildschirmtext, translated as Screentext) has been a German service, allowing to transfer data via telephone line. In the 8bit era, the Deutsche Bundespost (German postal service) still owned the monopoly for telecommunications in Germany, so the only legal way to transmit electronic data via telephone line has been to use their BTX service. The service was ultimatively suspended in 2007.

Beginning in late 2019, some work has begun to revive parts of the BTX service. There are [https://btx-museum.de/2020/02/29/der-neue-dbt-03-emulator/ emulators providing D-BT 03 ports], and some BTX pages were [https://www.heise.de/newsticker/meldung/36C3-Congress-wie-1984-mit-BTX-und-Originalarchiven-4624507.html restored by feeding recordings of original modem sessions to software demodulators].

== Pictures ==

<gallery>
File:SchneiderBtxModulCPC.jpg
File:SchneiderBtxModulCPC-close.jpg
File:SchneiderBtxModulCPC36486.jpg
File:SchneiderBtxModulCPC36486-2.jpg
</gallery>

=== PCB ===

<gallery>
File:Schneider BTX Modul - top.jpg|Top
File:Schneider BTX Modul - bottom.jpg|Bottom
</gallery>

== Case ==

'''Note''': Schneider also made a BTX module for Schneider Television Sets, although that device had nothing to do with the CPC, its housing was later re-used for the CPC's [[Schneider RS232 Interface]].

== Downloads ==

* [[Media:Schneider BTX Modul ROM dump.zip|Schneider BTX module ROM dump]]

== Weblinks ==

* http://en.wikipedia.org/wiki/Bildschirmtext - wikipedia article on BTX (english, short description)
* http://de.wikipedia.org/wiki/Bildschirmtext - wikipedia article on BTX (german, more detailed description)
* https://btx-museum.de/2020/02/29/der-neue-dbt-03-emulator/ (german)
* https://www.heise.de/newsticker/meldung/36C3-Congress-wie-1984-mit-BTX-und-Originalarchiven-4624507.html (german)

[[Category:Network]]

File:Schneider BTX Modul ROM dump.zip

2026-02-28T19:41:25Z

Octoate: User created page with UploadWizard

File:Schneider BTX Modul - bottom.jpg

2026-02-28T19:41:24Z

Octoate: User created page with UploadWizard

=={{int:filedesc}}==
{{Information
|description={{en|1=Bottom board of the Schneider BTX module}}
|date=2026-02-28 18:41:52
|source={{own}}
|author=[[User:Octoate|Octoate]]
|permission=
|other versions=
}}
{{Location dec|51.0252945|8.967071}}

=={{int:license-header}}==
{{self|cc-by-sa-4.0}}

[[Category:Uploaded with UploadWizard]]
[[Category:Hardware]]

File:Schneider BTX Modul - top.jpg

2026-02-28T19:41:23Z

Octoate: User created page with UploadWizard

=={{int:filedesc}}==
{{Information
|description={{en|1=Top board of the Schneider BTX module}}
|date=2026-02-28 18:41:34
|source={{own}}
|author=[[User:Octoate|Octoate]]
|permission=
|other versions=
}}
{{Location dec|51.025293361111|8.9670710833333}}

=={{int:license-header}}==
{{self|cc-by-sa-4.0}}

[[Category:Uploaded with UploadWizard]]
[[Category:Hardware]]

XzentriX Meeting 2016

2016-04-25T19:48:37Z

Octoate: added page for the XzentriX 2016

The '''[[XzentriX|XzentriX]] 2016''' takes place from 02.-04. September 2016 in Seeshaupt, Germany, and is - as always - organised by [[Mr. Ams|Mr. Ams]] and Robert Sterff. As usual it is a party for all old (8bit) computers from the 70ies, 80ies and early 90ies and it is the meeting with the highest attendance of german CPC users.

== Participiants ==

* [[Brainblaster]]
* [[MaV]]
* [[Mr.Ams]]
* [[Octoate]]
* [[Prodatron]]
* [[Tolkin]]

== Picture galleries ==

== Blog / News Entries ==

== Web links ==

*[http://www.xzentrix.de XzentriX homepage]

[[Category:CPC_events]]

XzentriX

2016-04-25T19:46:42Z

Octoate: /* Parties */ added XzentriX 2016

The XzentriX takes place every year in Seeshaupt, Germany, and is organised by Herbert Heppchen, Robert Sterff and [[Mr. Ams]]. It is a party for all old (8bit) computers and video games from the 70ies, 80ies and early 90ies.

== Parties ==

* [[XzentriX Meeting 2016]]
* [[XzentriX Meeting 2015]]
* [[XzentriX Meeting 2014]]
* [[XzentriX Meeting 2013]]
* [[XzentriX Meeting 2012]]
* [[XzentriX Meeting 2011]]
* [[XzentriX Meeting 2010]]
* [[XzentriX Meeting 2009]]
* [[XzentriX Meeting 2008]]
* [[XzentriX Meeting 2007]]
* [[XzentriX Meeting 2006]]
* [[XzentriX Meeting 2005]]
* [[XzentriX Meeting 2004]]
* [[XzentriX Meeting 2003]]
* [[XzentriX Meeting 2002]]
* [[XzentriX Meeting 2001]]
* [[XzentriX Meeting 2000]]
* [[XzentriX Meeting 1999]]

== Web links ==

* [http://www.xzentrix.de XzentriX homepage]

[[Category:CPC events]]

XzentriX Meeting 2015

2015-09-08T09:11:52Z

Octoate: XzentriX 2015

The '''[[XzentriX|XzentriX]] 2015''' took place from 04.-06. September 2015 in Seeshaupt, Germany, and was - as always - organised by [[Mr. Ams|Mr. Ams]] and Robert Sterff. As usual it is a party for all old (8bit) computers from the 70ies, 80ies and early 90ies and it is the meeting with the highest attendance of german CPC users.

== Participiants ==

* [[Brainblaster]]
* [[Dark Sector]]
* [[Kangaroo MusiQue]]
* [[MaV]]
* [[Mr.Ams]]
* [[Nurgle]]
* [[Octoate]]
* [[Odiesoft]]
* [[Odin]]
* [[Prodatron]]
* [[Tolkin]]

== Picture galleries ==

== Blog / News Entries ==

== Web links ==

*[http://www.xzentrix.de XzentriX homepage]

[[Category:CPC_events]]

XzentriX

2015-09-08T09:09:03Z

Octoate: added XzentriX 2015

The XzentriX takes place every year in Seeshaupt, Germany, and is organised by Herbert Heppchen, Robert Sterff and [[Mr. Ams]]. It is a party for all old (8bit) computers and video games from the 70ies, 80ies and early 90ies.

== Parties ==

* [[XzentriX Meeting 2015]]
* [[XzentriX Meeting 2014]]
* [[XzentriX Meeting 2013]]
* [[XzentriX Meeting 2012]]
* [[XzentriX Meeting 2011]]
* [[XzentriX Meeting 2010]]
* [[XzentriX Meeting 2009]]
* [[XzentriX Meeting 2008]]
* [[XzentriX Meeting 2007]]
* [[XzentriX Meeting 2006]]
* [[XzentriX Meeting 2005]]
* [[XzentriX Meeting 2004]]
* [[XzentriX Meeting 2003]]
* [[XzentriX Meeting 2002]]
* [[XzentriX Meeting 2001]]
* [[XzentriX Meeting 2000]]
* [[XzentriX Meeting 1999]]

== Web links ==

* [http://www.xzentrix.de XzentriX homepage]

[[Category:CPC events]]

Programming:CPC Booster

2015-01-03T23:02:19Z

Octoate: /* ADDRESS:&FF07 IN/OUT UART REG2 */ formatting...

''This article describes how to use the [[Antitec|Antitec's]] [[CPC Booster]] from [[BASIC]] and machine code. It is a direct conversion of the CPC Booster+ manual.''

== How to use the CPC Booster+ ==

The CPC booster+ is very easy to use, even through BASIC. In this document I will explain how to use all the functions of the card by analyzing the memory map. I will use both Assembly and Basic, but in most cases you will have to use only assembly to use the speedy characteristics (you can’t have 230400 baud serial communication in Basic!). The only thing you need is simple IN and OUT commands to give orders to the board. All the addresses are 16bit, but the high byte is always &FF for the CPC booster.

When you switch on your CPC, after one second the led of the card will be turned on. This means that the card is working. If during the operation the led flashes it means that the microcontroller is resetting itself because the power supply is insufficient. This may happen if you have an external drive connected which takes power from the CPC and not from an external power supply or if you have too many peripherals connected. In this case, send me an e-mail and we’ll see what we can do to avoid this problem. Be sure that you have connected the cable in the right way otherwise the led won’t flash at all.

The CPC Booster+ is an open source project. Since most of you know Z80 assembly, then it will be easy for you to write your own routines in AVR assembly, which is very similar to the Z80. Right now, there is a LOT of free space in the bios of the booster to fill it with anything you want. Imagine that the booster has a faster processor not only because of the crystal frequency of the 11.05292 MHz, but AVR is also a RISC processor, almost every command is executed in 1 machine cycle.

If you are willing to add your own routines, then don’t hesitate to contact me in order to give you all the software and details you need to write your own stuff. But I would advice you to send the changed source code back to me in order to spread it and keep one version of the bios for everyone. Don’t forget that an update of the bios is possible through the CPC.

If you also have trouble on using the booster, even after reading the manual, then contact me and perhaps we can make a forum that we could discuss about it. I can tell you that the booster’s capabilities can be a very long subject to analyze.

The CPC Booster hardware includes the following things:

*One RS232/485 serial port.
*Two Analog to digital converters (8 Bit) with rec level
*Two PWM channels, used as digital to analog converters
*One 5bit TTL in/out port
*512 Bytes EEPROM
*256 Bytes RAM buffer
*Keyboard scanning functions

'''WARNING:''' Before you use any of the fast routines, in most cases you have to disable the interrupts first:

<pre>
LD HL,&C9FB
LD (&38),HL

Or use DI
</pre>

== Functions ==

=== Memory map of the CPC Booster+ ===
<pre>
;****************************************************************
;MEMORY MAP OF THE CPC BOOSTER+

;00 IN 10101010 TEST BYTE #1
OUT 00-$FF RESET BOOSTER
;01 IN 01010101 TEST BYTE #2
OUT 00-$FF RESET BOOSTER

;02 OUT 00-$FF PWM CHANNEL 1
;03 OUT 00-$FF PWM CHANNEL 2

;04 IN/OUT 00-$FF UBRR/BAUD RATE
;05 IN/OUT 00-$FF UDR READ/WRITE
;06 IN/OUT 00-$FF UART REG 1
;07 IN/OUT 00-$FF UART REG 2
;08 OUT 00-$FF UART TX/AUTO POLLING
;09 IN 00/$FF UART WAIT UDR CHARACTER
;0A IN/OUT 00-$FF UART READ TIME OUT*50ms
;0B IN/OUT 000XXXXX UART REG 3

;0C IN/OUT 00-$01 EEPROM ADDRESS HIGH
;0D IN/OUT 00-$FF EEPROM ADDRESS LOW
;0E IN/OUT 00-$FF EEPROM READ/WRITE

;0F IN/OUT 00000XXX ADC SAMPLING FREQUENCY
;10 IN/OUT 00-$01 ADC CHANNEL SELECTION
;11 IN 00-$FF READ ADC VALUE

;12 IN/OUT 00-$FF KEYBOARD READ

;13 OUT 00-$7F PAGE WRITE FOR UPDATE
;14 OUT 00-$FF DATA FOR UPDATE BUFFER
;15 IN/OUT 00-$7F ADDRESS OF BUFFER FOR BIOS UPDATE

;16 IN/OUT 00-$7F ROM PAGE NUMBER
;17 IN/OUT 00-$7F ADDRESS OF PAGE
;18 IN 00-$FF READ ROM DATA (PAGE MODE)

;19 IN/OUT 00-$3F ROM ADDRESS HIGH
;1A IN/OUT 00-$FF ROM ADRESS LOW
;1B IN 00-$FF READ ROM DATA (ADDRESSING MODE)

;1C IN 00-$FF AVAILABLE CHARACTER IN UART BUFFER
OUT 00-&FF RESET UART BUFFER
;1D IN 00-$FF READ CHARACTER FROM BUFFER

;1E IN/OUT 00-$1F 5 BITS PORT DIRECTION SETTING
;1F IN/OUT 00-$1F 5 BITS PORT LATCH (OUTPUT)
;20 IN 00-$1F 5 BITS PORT INPUT

;21 OUT 00-$FF MULTIPLIER 1
;22 OUT 00-$FF MULTIPLIER 2
;23 IN 00-$FF RESULT HIGH BYTE
;24 IN 00-$FF RESULT LOW BYTE

;25 IN 00-$FF READ VERSION
OUT 00-$FF RESET TEXT ADDRESS

;26 OUT 00-$FF PWM BUFFERED STEREO
;27 OUT 00-$FF PWM MONO TO BOTH CHANNELS

;28 IN/OUT 00-$FF RAM BUFFER ADDRESS
;29 IN/OUT 00-$FF RAM BUFFER DATA
;2A IN/OUT 00-$FF RAM BUFFER DATA POST INCREMENT
</pre>

=== ADDRESS:&FF00 + &FF01 IN/OUT TEST BYTES / RESET ===

Those two addresses are used to test the board, mainly to check if the connector’s cable is working. If you type in BASIC

<pre>
?INP(&FF00),INP(&FF01)
</pre>

and you get the results 170 , 85 then the board is working. Address 00 always reads 170 and address 01 always reads 85. If you get any other values, then there must be a problem with your cable. Try moving the cable a little bit till you get the correct values. The CPC connector is a problematic one

If you make an OUT any value to those addresses, then the CPC booster makes a Reset.
<pre>
OUT &FF00,n or OUT &FF01,n (n = any value from 0 to 255)
</pre>

=== ADDRESS:&FF02 + &FF03 IN/OUT PWM CHANNELS ===

The board has two 8BIT PWM channels. PWM stands for Pulse Width Modulation, which means that it is an output that gives you pulses which we can alter their width. To alter the width, we send 8bit values to those addresses. To send a value to channel 1 for example, you type in BASIC

<pre>
OUT &FF02,X where X is the value we want to send
</pre>

In assembly we type
<pre>
 LD BC,&FF02
 LD A,X
OUT (C),A
</pre>

It’s the same thing for channel two: instead of &FF02, we use &FF03. If you make an in on any of those two channels, you can read the last value you sent. The output needs a pre-amplifier, or just a good amplifier. Due to the low-pass filter, which is used to turn the pulses into DC signals (the Digital to analog converter) , you will get a more bass sound. No need for digiblaster or soundplayer if you have a CPC Booster+, you can play stereo samples and the quality is good.

=== ADDRESS:&FF26 IN/OUT PWM BUFFERED STEREO ===

In order to have values played on both channels at the same time, you can use this address. First you send the value for PWM channel 1 which is buffered and when you send the value for PWM channel 2, both values are transferred to the output at the same time. If you make an IN, you clear the buffer and the routine is waiting again for a value for PWM channel 1. You can clear the buffer at first, you don’t have to clear it after every two values you send.

<pre>
LD BC,&FF26
IN A,(C) ;Clear the buffer
LOOP: LD A,X ;Value for channel 1
OUT (C),A ;Store the value to the buffer
LD A,Y ;Value for channel 2
OUT (C),A ;Now send both values to PWM channels
JR LOOP
</pre>

=== ADDRESS:&FF27 IN/OUT PWM VALUE TO BOTH CHANNELS ===

If you want to play mono samples at both channels, to have one value played at the same time to the two PWM channels, you can use this address.

<pre>
LD BC,&FF27
LD A,X
OUT (C),A ;Value is transfered to both channels PWM 1 & 2
</pre>

== The USART – Serial communication ==

The addresses from &FF04 to &FF0B are used for the UART, which means Universal synchronous/asynchronous receiver-transmitter. Or just RS232. I suggest you to use assembly though it’s possible to use Basic at low Baud rates. An important thing in high speed communication is to disable the interrupts first. We can control and set up the RS232 using three registers of the CPC Booster+: UART REG1, UART REG2 and UART REG3.

The CPC Booster+ has also an RS485 network. You can transmit to the RS485 and the RS232 at the same time but you can only read data from one of them. There’s a switch on the board which selects from which port to read data.

=== ADDRESS:&FF04 IN/OUT UBRR (Baud rate) ===

The address &FF04 is used to select the baud rate of the UART. It’s a value between 0-255 and it’s calculated like this:

UBRR= (( FREQUENCY / BAUDRATE) / 16 ) – 1
BAUDRATE= FREQUENCY / ((UBRR+1)*16)

In our case:
UBRR= ((11059200 / BAUDRATE) / 16 ) – 1
There are two modes to select the baud rate. The normal and the double speed (U2X) can be selected in the UART REG3 which will be described later.

<pre>
U2X=0 U2X=1
UBRR BAUDRATE BAUDRATE

4800 143 X
9600 71 143
14400 47 95
19200 35 71
28800 23 47
38400 17 35
57600 11 23
115200 5 11
230400 2 5
345600 1 3
691200 0 1
1382400 X 0
</pre>

If we want to select 57600, then we type in BASIC

<pre>
OUT &FF04,11
</pre>

And in assembly

<pre>
LD A,11
LD BC,&FF04
OUT (C) ,A
</pre>

We have the ability to read also the UBRR value we’ve selected

<pre>
?INP(&FF04) in BASIC
</pre>

and in assembly:

<pre>
LD BC,&FF04
IN A,(C)
</pre>

=== ADDRESS:&FF05 IN/OUT UDR READ/WRITE ===

This address has actually two separate functions, one for IN and one for OUT. When we use the IN command, we read the RX input of the UART and when we make an OUT, we transmit a value to the UART. But in order to use the UART properly, we will have to examine the flags first.

=== ADDRESS:&FF06 IN/OUT UART REGISTER 1 ===

'''RXC'''
'''TXC'''
'''UDRE'''
'''FE'''
'''DOR'''
'''PE'''
'''RXB8'''
'''TXB8'''

This register contains 6 flags in order to control the UART. To read them we use in Basic

<pre>
?INP(&FF06)
</pre>

and in assembly

<pre>
LD BC,&FF06
IN A,(C)
</pre>

'''BIT 7 – RXC: UART RECEIVE COMPLETE'''
This bit is set when the UART has received a character. So before we use the address &FF05 to read a value, we have to check first this bit to see if a character was received. This bit is cleared by reading the UDR (&FF05).

'''BIT 6 – TXC: UART TRANSMIT COMPLETE'''
This bit is set when the entire character was transmitted, including the stop bit. This is used mainly for half duplex communication, where you have to know when your character has been transmitted before you send the next one or to enter receive mode. This bit is cleared by writing a logical one to the bit.

'''BIT 5 – UDRE: UART DATA REGISTER EMPTY'''
This bit is set (one) when a character written to UDR (&FF05) is transferred to the transmit shift register of the microcontroller and the UDR is empty. When this bit is set it means that we can send a new character to UDR (&FF05). This bit is cleared when we send a character to UDR.

'''BIT 4 – FE: FRAMING ERROR'''
This bit is set if a framing error condition is detected, i.e. when the stop bit of an incoming character is zero. The FE bit is cleared when the stop bit of received data is one.

'''BIT 3 – OR: OverRun'''
This bit is set if an overrun condition is detected, i.e. when a character already present in the UDR register is not read before the next character has been shifted into the receiver shift register. The OR bit is buffered , which means that it will be set once the valid data still in UDRE is read. The OR bit is cleared when data is received and transferred to UDR.

'''BIT 2 – PE: Parity error'''
This bit is set if the next character of the UART had a parity error when received and the the parity checking was enabled at that point. This bit is valid until the UDR (&FF05) is read. Always set this bit to zero when writing to UART REG1.

'''BIT 1 – RXB8: Receive data bit 8'''
RXB8 is the ninth data bit of the received character when operating with serial frames with nine data bits. Must be read before reading the low bits from UDR.

'''BIT 0 – TXB8: Transmit data bit 8'''
TXB8 is the ninth data bit in the character to be transmitted when operating with serial frames with nine data bits. Must be written before writing the low bits to UDR.

OK, if those bits seem like chinese, don’t worry. Here are some routines to make things more clear:

BASIC – Receiving data
<pre>
10 A=INP(&FF06) ;READ THE FLAGS
20 A=A AND 128 ;CHECK THE RXC FLAG
30 IF A=0 THEN 10 ;IF RXC IS NOT SET THEN GOTO 10
40 A=INP(&FF05) ;READ THE CHARACTER (RXC IS NOW CLEARED)
50 PRINT A
60 GOTO 10
</pre>

ASSEMBLY – Receiving data
<pre>
 LD BC,&FF06
RX_LOOP: IN A,(C) ;Read the flags
 AND A,%10000000 ;Check if RXC bit is set
 JR Z,RX_LOOP ;If zero, goto RX_LOOP
 DEC C ;Select &FF05
 IN A,(C) ;Read the received character and clear the RXC
</pre>

BASIC – Sending a character / HALF DUPLEX communication
<pre>
10 A=X ;X is an 8bit character we want to transmit
20 OUT &FF05,A ;Send character
30 A=INP(&FF06) ;Read the flags
40 A=A AND 64 ;Leave only the TXC flag
50 IF A=0 THEN 30 ;Wait till the TXC flag is SET. The flag will be set when the entire character is transmitted
60 A=64 ;You can skip this since A is already 64
70 OUT &FF06,A ;Set the TXC bit to clear it (strange, isn’t it?)
80 GOTO 10
</pre>

ASSEMBLY- Sending a character / HALF DUPLEX communication
<pre>
 LD BC,&FF05
 LD A,X ;X= data we want to transmit
 OUT(C),A ;Send the character to UDR
 LD BC,&FF06
TXC_LOOP: IN A,(C) ;Read the flags
 ANDI A,%01000000 ;Check the TXC
 JR Z,TXC_LOOP ;If cleared, goto TXC_LOOP
 LD A,64 ;You can skip this
 OUT (C),A ;Clear the TXC by writing a logic one to it.
</pre>

BASIC – Sending a character / FULL DUPLEX communication
<pre>
10 A=INP(&FF06) ;Read the flags
20 A=A AND 32 ;Check the UDRE bit
30 IF A=0 THEN 10 ;If UDRE is cleared, then the UART is not ready to send a new character
40 A=X ;X= Data we want to transmit
50 OUT (&FF05),A ;Transmit data
</pre>

ASSEMBLY – Sending a character / FULL DUPLEX communication
<pre>
 LD BC,&FF06
UDRE_LOOP: IN A,(C) ;Read the flags
 AND A,32 ;Check the UDRE bit
 JR Z,UDRE_LOOP ;If zero, goto UDRE_LOOP
 LD A,X ;X= data we want to transmit
 LD BC,&FF05
 OUT(C),A ;Transmit character
</pre>

=== ADDRESS:&FF07 IN/OUT UART REG2 ===

'''UMSEL'''
'''UPM1'''
'''UPM0'''
'''USBS'''
'''UCSZ2'''
'''UCSZ1'''
'''UCSZ0'''
'''UCPOL'''

This register contains settings for the UART.

'''BIT 7 – UMSEL: USART mode select'''
This bit selects between asynchronous (0) and synchronous (1) mode of operation.

'''BITS 6,5 – UPM1,UPM0: Parity Mode'''
These bits enable and set type of parity generation and check. If enabled, the transmitter will automatically generate and send parity of the transmitted data bits within each frame. The receiver will generate a parity value for the incoming data and compare it to the UPM setting. If a mismatch is detected, the PE flag in UART REG1 will be set

<pre>
UPM1 UPM0 Parity mode

0 0 Disabled
1 0 Even parity
1 1 Odd parity
</pre>

'''BIT 4 – USBS: Stop bit select'''
This bit selects the number of Stop bits to be inserted by the transmitter. The receiver ignores this setting.
<pre>
USBS=0 1 stop bit
USBS=1 2 stop bits
</pre>

'''BIT 3,2,1 – UCSZ2,UCSZ1,UCSZ0: Character size'''
The UCSZ2:1:0 bits set the number of data bits (character size) in a frame the receiver and transmitter use.

<pre>
UCSZ2 UCSZ1 UCSZ0 Character size
0 0 0 5 bit
0 0 1 6 bit
0 1 0 7 bit
0 1 1 8 bit
1 1 1 9 bit
</pre>

'''BIT 0 – UCPOL: Clock polarity'''
This bit is used for synchronous mode only. Write this bit to zero when asynchronous mode is used. The UCPOL bit sets the relationship between data output change and data input sample, and the synchronous clock (XCK).

<pre>
Transmitted data changed (TX pin) Received data sampled (RX pin)

UCPOL=0 Rising XCK edge Falling XCK edge
UCPOL=1 Falling XCK edge Rising XCK edge
</pre>

=== ADDRESS:&FF08 OUT TX – AUTO POLLING ===

If you want to transmit a character in a full duplex or a half duplex communication then you just send the character to the address &FF08 and the flags are automatically checked by the program of the microcontroller!

<pre>
BASIC: A=X
OUT &FF08,A
</pre>

<pre>
ASSEMBLY: LD BC,&FF08
LD A,X
OUT(C),A
</pre>

To select the type of communication you want to have (full duplex, half duplex or 485 halfduplex), you can use UART REG3.

=== ADDRESS:&FF09 IN RX – WAIT UDR CHARACTER ===
=== ADDRESS:&FF0A IN/OUT TIME OUT VALUE * 50msec ===

The address &FF09 uses a time-out function. When you make an IN from this address, if a character is received, you’ll read the value 255, if no character appears after a time-out then you will read the value 0. To set the time-out, we use the address &FF0A. Examples in BASIC and assembly:

BASIC – Receiving a character
<pre>
10 OUT &FF0A,10 ;Set the time out at 10*50= 500 msec
20 A=INP(&FF09) ;Check if there is an available character in UDR
30 IF A=0 THEN 50 ;If after 500msec no character appears then we
;get the result 0
40 A=INP(&FF05):END ;Else, we read the received character
50 PRINT “NO CHARACTER”
</pre>

ASSEMBLY- Receiving a character
<pre>
 LD A,10
 LD BC,&FF0A
 OUT(C),A ;Set the time out at 10*50= 500msec
 LD BC,&FF09
RX_LOOP: IN A,(C) ;Check if there is an available character in UDR
 CP A,0 ;If A=0 then goto RX_LOOP
 JR Z,RX_LOOP
 LD BC,&FF05
 IN A,(C) ;Read the received character
</pre>

As I said above, when you make an IN from address &FF09, if no character is received, you’ll get the value 0 after the time out, in our example the 500msec. But as soon as a character is received, you’ll get immediately the value 255, you won’t have to wait the 500msec to pass.

=== ADDRESS:&FF0B IN/OUT UART REG3 ===

'''UART BUFFER ON/OFF'''
'''U2X'''
'''485 AUTO POLLING'''
'''FULL/HALF DUPLEX'''
'''MASTER/SLAVE'''

Only the 5 low bits are used in this register. Bits 7,6 and 5 are always read as zero.

'''BIT 4 – UART BUFFER ON/OFF: Enables/disables the UART buffer.'''
The CPC booster has a buffer of 255 bytes for the UART which improves the communication. It can be enabled by writing 1 to this bit. More details about the buffer in the following addresses.

'''BIT 3 – U2X: Double UART speed'''
This bit selects between normal and double speed for the UART. To calculate UBRR when the double speed is selected you use this:

UBRR= (( FREQUENCY / BAUDRATE) / 8 ) – 1

BAUDRATE= FREQUENCY / ((UBRR+1)*8)

'''BIT 2 – 485 AUTO POLLING'''
If BIT 1 of UART REG3 is set (half duplex selected) then the Master/Slave pin of the 485 is automatically driven by the CPC Booster when you use the routine of TX AUTO POLLING (&FF08). If BIT 1 is reset (full duplex selected), then this bit has no effect.

'''BIT 1 – FULL/HALF DUPLEX'''
With this bit you can select the type of communication to use with the TX AUTO POLLING (&FF08) routine.

0=FULL DUPLEX

1=HALF DUPLEX

'''BIT 0 – MASTER/SLAVE'''
This bit directly drives the pin of TX/RX enable of the 485. Whenever you want to transmit something to the 485 you have to set this bit and after the transmission is over, you have to reset it. By setting BIT 1 and BIT 2 of the UART REG3, this pin is driven automatically by the CPC booster when you use the TX AUTO POLLING routine.

Except for the 485, this bit is also connected to the RS232 port as the Carrier Detect signal.

== UART Buffering ==

While I was trying to make my terminal program, I figured out that our CPC is kind of slow for terminal emulation. Imagine what a terminal program does: Checks for incoming characters, prints them, scans the keyboard, prints and transmits the pressed keys. The CPC was losing bytes even at very low speed. At first I thought of installing a buffer on the CPC. I did that and there was a huge improvement but still every now and then , some bytes were missing. So I thought about installing a buffer inside the CPC booster. And it really works! The communication is perfect even at 230400!

The UART buffer is 255 bytes long. It can be enabled or disabled. If the buffer is enabled then you shouldn’t use &FF05 or &FF06 to read incoming characters cause you will mess with the buffer. If the buffer is disabled you use the old routines without changing anything. Enabling the buffer affects only the incoming characters, the transmitting methods (half duplex/full duplex) remain the same.

=== ADDRESS:&FF1C IN/OUT NUMBER OF AVAILABLE BYTES IN BUFFER / RESET BUFFER ===
=== ADDRESS:&FF1D IN READ DATA FROM BUFFER ===

If the buffer is enabled, then the address &FF1C contains the number of available characters in the buffer when you make an IN. Making an OUT any value at this address, resets the buffer.

To enable/disable the buffer, you use BIT 4 of UART REG3.

When you make an IN from the address &FF1D, then you read the incoming data from the buffer, and the number of available bytes in the buffer decreases. When characters are received, then the number of bytes in the buffer increases.

An example in BASIC
<pre>
10 OUT &FF0B,16 ;Enable the buffer
20 OUT &FF1C,0 ;Reset the buffer
30 IF INP(&FF1C)=0 THEN 30 ;Wait for incoming characters in the buffer
40 ?INP(&FF1D) ;Print data from the buffer
50 GOTO 30
</pre>

An example in Assembly (don’t worry, I know that the code is not optimized :))
<pre>
LD A,16
LD BC,&FF0B
OUT(C),A ;Enable the buffer
LD A,1
LD BC,&FF1C
OUT(C),A ;Reset the buffer

LOOP: LD BC,&FF1C
IN A,(C)
CP A,0 ;Loop until a character appears
JR Z,LOOP
LD BC,&FF1D
IN A,(C) ;Read data from buffer
CALL &BB5A ;Print data
JR LOOP
</pre>

== 512 Bytes EEPROM ==

Since the microcontroller had the EEPROM, I thought that I should give the ability for the CPC to access it. I know it’s not much but incase you want to save some settings, it's quite good. Anyway, the addresses are from 0 till 511 (0-&1FF in HEX). Address 0 shouldn’t be used because it’s reserved for the bios protection routine.

=== ADDRESS:&FF0C IN/OUT EEPROM ADDRESS HIGH BYTE ===
=== ADDRESS:&FF0D IN/OUT EEPROM ADDRESS LOW BYTE ===

The high byte can only be 0 or 1, a value bigger than 1 will be automatically changed to 1

=== ADDRESS:&FF0E IN/OUT EEPROM READ/WRITE ===

This accesses the byte of the address of the EEPROM we’ve selected with the addresses &FF0C and &FF0D. Here are some examples in BASIC
<pre>
10 OUT &FF0C,0
20 OUT &FF0D,5 ;Select address 5
30 OUT &FF0E,25 ;Store the value 25 at the address 5
40 OUT &FF0C,&1
50 OUT &FF0D,&4E ;Select address &14E (334 in decimal)
60 A=INP(&FF0E) ;Read the contents of the address &14E
70 PRINT A
</pre>

== The Analog to Digital Converter ==

The CPC booster gives you the ability to make 8bit samples on the CPC. Ofcourse, there were some samplers in the past for the CPC, like the Music Machine, but this time it’s easier than ever! The sampler can be used only through assembly because in Basic the sampling rate is worse than an 1 bit sample!

=== ADDRESS:&FF0F IN/OUT ADC SAMPLING FREQUENCY ===

With this address, we can select the sampling rate. We don’t have to make complicated routines on the CPC, the baud rate can be set directly on the CPC booster, so we just make a simple IN to get the data and all the timing is done automatically. There are 8 possible values to select frequency, value 0 and 1 are the same:

<pre>
VALUE DIVISION FACTOR SAMPLING FREQUENCY
0 2 5529 KHz
1 2 5529 KHz
2 4 2764 KHz
3 8 1382 KHz
4 16 691 KHz
5 32 345 KHz
6 64 172 KHz
7 128 86 KHz
</pre>

As you understand, if the frequency is high, you have good quality but it takes a lot of memory and you can’t make long samples. In the worst quality, 86 KHz, you can create around 14 sec long sample, which takes 64 KB.

<pre>
ASSEMBLY: LD A,3 ;Select 1382 KHz sampling freq.
 LD BC,&FF0F
 OUT(C),A
</pre>

=== ADDRESS:&FF10 IN/OUT ADC CHANNEL SELECTION ===

With this address you select from which channel you will get the data. There are two channels, so we have the possibility to make stereo samples, or to record a stereo sample from a music CD and turn it into mono. To select channel 1, we send the value 0, to select channel 2 we send value 1. Any value between 2 and 255 selects channel 1 again (I’ve just noticed that!).

<pre>
ASSEMBLY: LD A,0 ;Select channel 1
 LD BC,&FF10
 OUT(C),A
</pre>

=== ADDRESS:&FF11 IN READ ADC VALUE ===

To read the data from the A/D convertor, we make an IN from this address. Could it be simplier? Here’s a routine which stores a sample with max width 10KB

<pre>
 LD HL,16384 ;Address to store the sample
 LD DE,10000 ;Byte counter (10KB long sample)
 LD BC,&FF11 ;Address for reading data
SAMPLE: IN A,(C) ;Read byte from the convertor
 LD(HL),A ;Store byte in the address that HL points
 INC HL ;Increase sample address to store next byte
 DEC DE ;Decrease counter
 LD A,D
 OR E
 JR NZ,SAMPLE ;Check if sample is 10KB long.
</pre>

During the recording of a sample, you can adjust the incoming record volume with the potensiometer located on the top of the CPC booster. Use a screwdriver and adjust it till you get a clear sound. A way to do this adjustment is to make an in with &FF11 and send the value directly to the PWM.

=== ADDRESS:&FF12 IN/OUT KEYBOARD SCANNING FUNCTIONS ===

The functions on the address &FF12 are combined with a routine on the CPC. What this routine does is by having the 10 bytes of the CPC keyboard scan, can return to you the pressed key. There is a table which will help you find out the exact key pressed. This routine can only be used in an editor, when you can only press one key at a time (combined with shift).
First of all, let's see the routine on the CPC. What this routine does is making the whole keyboard scan and sending each line's byte to the CPC Booster.

<pre>
LD BC,&FF12:IN A,(C) ;Making a false read in the beginning of the program just to reset the routine
... MAIN PROGRAM ...
CALL KEYSCAN ;Call routine to scan the CPC keyboard
LD BC,&FF12
IN A,(C) ;Get pressed key
... JUMP TO MAIN PROGRAM ...
KEYSCAN: LD BC,&F40E:OUT(C),C
LD BC,&F6C0:OUT(C),C
DB &ED,&71
LD BC,&F792:OUT(C),C
LD BC,&F640:OUT(C),C:LD B,&F4:IN A,(C):LD BC,&FF12:OUT(C),A ;Read the byte from the scanned line
LD BC,&F641:OUT(C),C:LD B,&F4:IN A,(C):LD BC,&FF12:OUT(C),A ;and send it to the CPC booster
LD BC,&F642:OUT(C),C:LD B,&F4:IN A,(C):LD BC,&FF12:OUT(C),A
LD BC,&F643:OUT(C),C:LD B,&F4:IN A,(C):LD BC,&FF12:OUT(C),A
LD BC,&F644:OUT(C),C:LD B,&F4:IN A,(C):LD BC,&FF12:OUT(C),A
LD BC,&F645:OUT(C),C:LD B,&F4:IN A,(C):LD BC,&FF12:OUT(C),A
LD BC,&F646:OUT(C),C:LD B,&F4:IN A,(C):LD BC,&FF12:OUT(C),A
LD BC,&F647:OUT(C),C:LD B,&F4:IN A,(C):LD BC,&FF12:OUT(C),A
LD BC,&F648:OUT(C),C:LD B,&F4:IN A,(C):LD BC,&FF12:OUT(C),A
LD BC,&F649:OUT(C),C:LD B,&F4:IN A,(C):LD BC,&FF12:OUT(C),A
LD BC,&F782:OUT(C),C:LD BC,&F600:OUT(C),C:RET
</pre>

The routine in the CPC booster, after receiving 10 bytes, it will automatically find the pressed key and will give you its value when you will make an IN from the address &FF12. If we send 9 bytes or any value less than 10, then we will read 0. You have to send 10 bytes to get a correct response. Here’s the table with the returned values:

<pre>
00=No key 128=No key
01=a 129=A
02=b 130=B
03=c 131=C
04=d 132=D
05=e 133=E
06=f 134=F
07=g 135=G
08=h 136=H
09=i 137=I
10=j 138=J
11=k 139=K
12=l 140=L
13=m 141=M
14=n 142=N
15=o 143=O
16=p 144=P
17=q 145=Q
18=r 146=R
19=s 147=S
20=t 148=T
21=u 149=U
22=v 150=V
23=w 151=W
24=x 152=X
25=y 153=Y
26=z 154=Z
27=1 155=!
28=2 156=”
29=3 157=#
30=4 158=$
31=5 159=%
32=6 160=&
33=7 161=’
34=8 162=(
35=9 163=)
36=0 164=_
37=- 165==
38=^ 166=EURO
39=@ 167=|
40=[ 168={
41=: 169=*
42=; 170=+
43=] 171=}
44=, 172=<
45=. 173=>
46=/ 174=?
47=\ 175=`
48=f0
49=f1
50=f2
51=f3
52=f4
53=f5
54=f6
55=f7
56=f8
57=f9
58=f.
59=cursor left
60=cursor right
61=cursor up
62=cursor down
63=CLR
64=DEL
65=RETURN
66=ENTER
67=SPACE
68=COPY
69=CAPS LOCK
70=CONTROL
71=TAB
72=ESC
</pre>

As you can see, you can check bit7 to see if the shift key is pressed or not. To transform these values into ascii, you can use a 256 bytes page alligned table and a small routine:

<pre>
LD BC,&FF12
IN A,(C)
LD L,A
LD H,High byte of the table’s address
LD A,(HL)
</pre>

== Program memory read/write ==

The AVR mega16 has 16KB of program memory. The CPC booster gives you the ability to read and write this memory, that’s why the update of the peripheral is possible. Right now, less than 5 KB of this memory is used for the bios of the CPC booster, so you have around 10KB for your own purposes. Ofcourse, you already know that you should be careful to which address you will store your data, because you may accidentally erase data. If this happens, then you should try to re-update the bios and if that fails, then you will have to send the microcontroller back to me to re-program it.

A few words about the memory of the microcontroller. It is divided into 128 pages of 128 bytes each. 128*128=16384 bytes. Every command of the AVR is 16bit, which means that it takes two bytes. There are two ways to use the program memory through the CPC Booster, the page mode and the address mode. In the page mode, you select the address using two registers, one contains the page number and the other the address inside the page. In the address mode, the memory is divided like a normal ram, there are 16384 addresses of 8 bit each. You use two registers, one for the high byte and one for the low byte.

You can use both ways when you want to read the program memory but you can only store data using the page mode.

<pre>
ADDRESS:&FF13 OUT WRITE PAGE
ADDRESS:&FF14 OUT STORE BYTES TO PAGE BUFFER
ADDRESS:&FF15 IN/OUT ADDRESS OF THE PAGE BUFFER
</pre>

To write a page you have to fill the data into a buffer and then make an out at the address &FF13. To explain it better, here’s a small basic program to store data to a page.

<pre>
10 ADDRESS=16384 ;Source address data from the CPC
20 PAGE=80 ;We will write the data to page 80 (0-127)
30 FOR BUFFER=0 TO 127 ;Storing 128 bytes
40 OUT &FF14,PEEK(ADDRESS) ;Sending each byte to the CPC booster buffer. This function auto increases the buffer’s address.
50 ADDRESS=ADDRESS+1
55 NEXT BUFFER
60 OUT &FF13,PAGE ;After filling the buffer, write the data to the selected page.
</pre>

The address &FF15, points at the next address of the buffer. If we make an OUT &FF14,X, then the contents of the &FF15 will be automatically increased. Ofcourse, when it reaches 128, it goes back to 0. You can use this address if you want to reset the buffer or to see how many bytes you‘ve already stored inside the buffer. Kind of useless function but anyway.

== Write BIOS protection ==

From bios V1.5A and on, to be able to write data to the program memory, you have to disable the write bios protect option. To disable write bios protect, you have to write the value &CC to the EEPROM address 0. Any other value, forbids the controller to write data to the program memory.

<pre>
10 OUT &FF0C,0
20 OUT &FF0D,0
30 OUT &FF0E,&CC ;DISABLE WRITE BIOS PROTECTION
</pre>

<pre>
ADDRESS:&FF16 IN/OUT PAGE NUMBER
ADDRESS:&FF17 IN/OUT ADDRESS INSIDE PAGE
ADDRESS:&FF18 IN READ DATA
</pre>

Those addresses are used to read data from the program memory using the page mode. Address &FF16 contains the page you want to read, address &FF17 contains the address inside the page (0-127) and using &FF18 after you set the previous addresses, you read the data.

<pre>
EXAMPLE IN BASIC

10 PAGE=27
20 ADDRESS=0
30 OUT &FF16,PAGE
40 OUT &;FF17,ADDRESS
50 ?INP(&FF18)
</pre>

=== ADDRESS:&FF19 IN/OUT ADDRESS HIGH BYTE ===
=== ADDRESS:&FF1A IN/OUT ADDRESS LOW BYTE ===
=== ADDRESS:&FF1B IN READ DATA ===

I don’t think that you need further explanations... I remind you that the addresses are from 0 till 16383.

== TTL input/output ==

This is a 5 bit port which can be used as input/output for TTL signals. I think that it’s one of the most important characteristics of the CPC Booster because it gives you the ability to have a parallel port even if you only have 5 bits to control. People who like electronics and especially digital circuits already know how important this is.

The port is bi-directional with optional internal pull-ups.
<pre>
ADDRESS:&FF1E IN/OUT 5 BIT PORT DATA DIRECTION (DDx)
ADDRESS:&FF1F IN/OUT 5 BIT PORT DATA REGISTER (PORTx)
ADDRESS:&FF20 IN 5 BIT PORT INPUT (PINx)
</pre>

Those are the three addresses to control the port. Each one has 5 bits which control the 5 pins of the outport.

We can name the bits as DDx, PORTx and PINx. The DDx bit in the Data direction register selects the direction of the x pin (output or input). If the bit is zero, then the pin is an input, if it is set then the pin is an output.

If PORTx is set when the pin is configured as an input by the DDx bit, then the internal pull-up resistor is activated. To switch the pull-up resistor off, PORTx has to be zero or the pin must be configured as an output.

If PORTx is set when the pin is configured as an output pin, the port pin is driven high (5 Volts output). If PORTx is zero when the pin is configured as an output pin, then the port pin is driven low (0 Volts output).

Independent of the setting of the Data direction bit (DDx), the port pin can be read through the PINx register bit.

Some examples:
<pre>
LD A,%11111
LD BC,&FF1E
OUT (C),A ;All the pins are set as output pins
LD A,%10101
LD BC,&FF1F
OUT (C),A ;Pins 1,3 and 5 are driven high and
;pins 2 and 4 are driven low.

LD A,%11001
LD BC,&FF1E
OUT (C),A ;Pins 1,4,5 are configured as outputs.
LD A,%10111
LD BC,&FF1F
OUT (C),A ;Pins 1 and 5 are driven high. In pins 2 and 3,
;the internal pull-ups are activated.
LD BC,&FF20
IN A,(C) ;A has the state of each of the 5 pins.
</pre>

A pull-up resistor is used when we set a pin as an input. Incase we have nothing connected to that pin externally, if we read the PINx register bit, we will get the value 1 because it’s internally connected to the VCC through a resistor. A signal connected to the ground through a switch can drive this pin low. If you want to connect a button or a switch, one pin of the switch is connected to the ground and the other to the CPC Booster pin.

When the button is not pressed, you read “1” because of the internal pull-up. When the button is pressed, then the ground is connected to the pin and you read “0”. I can’t give you any more information about the TTL signals and the use of pull-ups because this is a manual for the CPC booster, not a lesson in electronics. But you can have a look at the PDF of the ATMega16, where the functions of the pins are described in a better way.

The pins are from left to right (TOP VIEW OF THE CPC BOOSTER):
<pre>
GND, PIN1, PIN2, PIN3, PIN4, PIN5
</pre>

== Multiplication ==

=== ADDRESS:&FF21 IN/OUT MULTIPLIER 1 ===
=== ADDRESS:&FF22 IN/OUT MULTIPLIER 2 ===
=== ADDRESS:&FF23 IN RESULT HIGH BYTE ===
=== ADDRESS:&FF24 IN RESULT LOW BYTE ===

I think that this function is very easy. First you give a value for multiplier 1 and then you give a value for multiplier 2. Whenever you enter a value to multiplier 2, a multiplication between multiplier 1 and multiplier 2 is done and the result is stored in addresses &FF23 and &FF24. The result will remain intact as long as the next multiplication takes place.

This is a multiplication between two 8 bit numbers and the result will be a 16 bit number.
<pre>
10 INPUT "MULTIPLIER 1";A
20 INPUT "MULTIPLIER 2";B
30 OUT &FF21,A
40 OUT &FF22,B
50 PRINT INP(&FF23)*256+INP(&FF24)
</pre>

== Read version number of the CPC Booster+ ==

=== ADDRESS:&FF25 IN/OUT READ VERSION / RESET TEXT POINTER ===

You can read some info of the booster+ you have using this routine:
<pre>
10 OUT &FF25,0 ;RESET TEXT POINTER
20 A=INP(&FF25)
30 IF A=0 THEN END
40 PRINT CHR$(A);
50 GOTO 20
</pre>

== 256 Bytes RAM Buffer ==

=== ADDRESS:&FF28 IN/OUT READ/WRITE RAM ADDRESS ===
=== ADDRESS:&FF29 IN/OUT READ/WRITE RAM DATA ===
=== ADDRESS:&FF2A IN/OUT READ/WRITE RAM DATA POST INCREMENT ===

With BIOS VERSION 1.5, you have the ability to use 256 bytes RAM of the AVRMEGA16 as a buffer to store temporary data. It’s not eeprom, if the CPC booster+ resets, then the data are gone. With &FF28 you select the address, with &FF29 you read/write data to the buffer and with &FF2A, after reading/writing data, the address increases automatically by one.

[[Category:Programming]]

XzentriX Meeting 2014

2014-09-15T09:28:39Z

Octoate: party is over, removed MaV, added Tolkin

The '''[[XzentriX|XzentriX]] 2014''' took place from 12.-14. September 2014 in Seeshaupt, Germany, and was - as always - organised by [[Mr. Ams|Mr. Ams]] and Robert Sterff. As usual it is a party for all old (8bit) computers from the 70ies, 80ies and early 90ies and it is the meeting with the highest attendance of german CPC users.

== Participiants ==

* [[Brainblaster]]
* [[Hiroyuki]]
* [[Kangaroo MusiQue]]
* [[Mr.Ams]]
* [[Nurgle]]
* [[Nilquader]]
* [[Octoate]]
* [[Odiesoft]]
* [[Odin]]
* [[Prodatron]]
* [[Tolkin]]

== Picture galleries ==

== Blog / News Entries ==

== Web links ==

*[http://www.xzentrix.de XzentriX homepage]

[[Category:CPC_events]]

XzentriX Meeting 2014

2014-09-09T15:56:44Z

Octoate: /* Participiants */ added more participants

The '''[[XzentriX|XzentriX]] 2014''' will take place from 12.-14. September 2014 in Seeshaupt, Germany, and will be - as always - organised by [[Mr. Ams|Mr. Ams]] and Robert Sterff. As usual it is a party for all old (8bit) computers from the 70ies, 80ies and early 90ies and it is the meeting with the highest attendance of german CPC users.

== Participiants ==

* [[Brainblaster]]
* [[Hiroyuki]]
* [[Kangaroo MusiQue]]
* [[MaV]]
* [[Mr.Ams]]
* [[Nurgle]]
* [[Nilquader]]
* [[Octoate]]
* [[Odiesoft]]
* [[Odin]]
* [[Prodatron]]

== Picture galleries ==

== Blog / News Entries ==

== Web links ==

*[http://www.xzentrix.de XzentriX homepage]

[[Category:CPC_events]]

XzentriX Meeting 2014

2014-08-03T15:06:37Z

Octoate: /* Participiants */

The '''[[XzentriX|XzentriX]] 2014''' will take place from 12.-14. September 2014 in Seeshaupt, Germany, and will be - as always - organised by [[Mr. Ams|Mr. Ams]] and Robert Sterff. As usual it is a party for all old (8bit) computers from the 70ies, 80ies and early 90ies and it is the meeting with the highest attendance of german CPC users.

== Participiants ==

* [[Brainblaster]]
* [[Hiroyuki]]
* [[MaV]]
* [[Mr.Ams]]
* [[Octoate]]

== Picture galleries ==

== Blog / News Entries ==

== Web links ==

*[http://www.xzentrix.de XzentriX homepage]

[[Category:CPC_events]]

XzentriX Meeting 2014

2014-04-27T10:12:39Z

Octoate: new page for the XzentriX 2014

The '''[[XzentriX|XzentriX]] 2014''' will take place from 12.-14. September 2014 in Seeshaupt, Germany, and will be - as always - organised by [[Mr. Ams|Mr. Ams]] and Robert Sterff. As usual it is a party for all old (8bit) computers from the 70ies, 80ies and early 90ies and it is the meeting with the highest attendance of german CPC users.

== Participiants ==

* [[Brainblaster]]
* [[MaV]]
* [[Mr.Ams]]
* [[Octoate]]

== Picture galleries ==

== Blog / News Entries ==

== Web links ==

*[http://www.xzentrix.de XzentriX homepage]

[[Category:CPC_events]]

XzentriX

2014-04-27T10:09:34Z

Octoate: /* Parties */ added XzentriX 2014

The XzentriX takes place every year in Seeshaupt, Germany, and is organised by Herbert Heppchen, Robert Sterff and [[Mr. Ams]]. It is a party for all old (8bit) computers and video games from the 70ies, 80ies and early 90ies.

== Parties ==

* [[XzentriX Meeting 2014]]
* [[XzentriX Meeting 2013]]
* [[XzentriX Meeting 2012]]
* [[XzentriX Meeting 2011]]
* [[XzentriX Meeting 2010]]
* [[XzentriX Meeting 2009]]
* [[XzentriX Meeting 2008]]
* [[XzentriX Meeting 2007]]
* [[XzentriX Meeting 2006]]
* [[XzentriX Meeting 2005]]
* [[XzentriX Meeting 2004]]
* [[XzentriX Meeting 2003]]
* [[XzentriX Meeting 2002]]
* [[XzentriX Meeting 2001]]
* [[XzentriX Meeting 2000]]
* [[XzentriX Meeting 1999]]

== Web links ==

* [http://www.xzentrix.de XzentriX homepage]

[[Category:CPC events]]

AMSDOS Header

2014-03-23T21:03:01Z

Octoate: wrong byte offsets for file length and checksum (thanks to Targhan)

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 is consists of 128 bytes and contains the following data:

<pre>
Byte 00: User number
Byte 01 to 08: filename
Byte 09 bis 11: Extension
Byte 18: type-byte
Byte 21 and 22: loading address
Byte 24 and 25: file length
Byte 26 and 27: execution address for machine code programs
Byte 64 and 65: (file length)
Byte 67 and 68: checksum for byte 00 to byte 66
</pre>

To calculate the checksum, just add byte 00 to byte 66 to each other.

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

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

XzentriX Meeting 2013

2013-09-18T07:41:47Z

Octoate: /* Picture galleries */ meeting pictures by Odiesoft and me

The '''[[XzentriX|XzentriX]] 2013''' took place from 06.-08. September 2013 in Seeshaupt, Germany, and was - as always - organised by [[Mr. Ams|Mr. Ams]] and Robert Sterff. As usual it is a party for all old (8bit) computers from the 70ies, 80ies and early 90ies and it is the meeting with the highest attendance of german CPC users.

== Participiants ==

* [[Kangaroo MusiQue]]
* [[MaV]]
* [[Mr.Ams]]
* [[Nilquader]]
* [[Nurgle]]
* [[Octoate]]
* [[Odiesoft]]
* [[Odin]]
* [[Sync]]

== Picture galleries ==
* [http://www.octoate.de/wp/meeting-gallery/nggallery/meeting-gallery/xzentrix-meeting-6-9-8-9-2013/ Pictures by Octoate]
* [http://odiesoft.de/galleries/xzentrix2013/index.html Pictures by Odiesoft]

== Blog / News Entries ==
* Octoate.de: [http://www.octoate.de/wp/2013/09/11/xzentrix-2013-meeting-pictures/ XzentriX 2013 meeting pictures]
* Heise Newsticker: [http://www.heise.de/newsticker/meldung/1-Vintage-Computer-Festival-in-der-Schweiz-1951922.html 1. Vintage Computer Festival in der Schweiz]

== Web links ==

*[http://www.xzentrix.de XzentriX homepage]

[[Category:CPC_events]]

XzentriX Meeting 2013

2013-09-18T07:39:22Z

Octoate: /* Blog Entries */ added news and blog entries

The '''[[XzentriX|XzentriX]] 2013''' took place from 06.-08. September 2013 in Seeshaupt, Germany, and was - as always - organised by [[Mr. Ams|Mr. Ams]] and Robert Sterff. As usual it is a party for all old (8bit) computers from the 70ies, 80ies and early 90ies and it is the meeting with the highest attendance of german CPC users.

== Participiants ==

* [[Kangaroo MusiQue]]
* [[MaV]]
* [[Mr.Ams]]
* [[Nilquader]]
* [[Nurgle]]
* [[Octoate]]
* [[Odiesoft]]
* [[Odin]]
* [[Sync]]

== Picture galleries ==

== Blog / News Entries ==
* Octoate.de: [http://www.octoate.de/wp/2013/09/11/xzentrix-2013-meeting-pictures/ XzentriX 2013 meeting pictures]
* Heise Newsticker: [http://www.heise.de/newsticker/meldung/1-Vintage-Computer-Festival-in-der-Schweiz-1951922.html 1. Vintage Computer Festival in der Schweiz]

== Web links ==

*[http://www.xzentrix.de XzentriX homepage]

[[Category:CPC_events]]

XzentriX Meeting 2013

2013-09-08T21:52:44Z

Octoate: /* Participiants */ - added Sync

2013-03-07T22:06:17Z

Octoate: added category and internal link to ROMAN website

Roman

2013-03-07T21:58:49Z

Octoate: added screenshots

ROMAN is a ROM-Manager for AMSDOS developed by [[Brueggi]] of [[PNG]]. ROMAN is fully compatible with the MegaFlash-ROM-Board from [[Bryce]] and to the [[SYMBiFACE II]] from [[Dr. Zed]] and will be compatible with the upcoming [[MegaFlash EX]] from [[SPRING]]/[[PNG]].

One highlight of ROMAN is its ROM-generator, wich can be used to generate ROMs out of normal binary programms. You can add an RSX-command to start the programm directly out of the generated ROM.

You can use ROMs with or without headers as BIN or ASCII. The ROMAN can also be used directly as a ROM itself. Start the ROMAN by running “DISC” and burn ROMAN.ROM to a ROM-Number of your choice. Start ROMAN from ROM by using the RSX-Command:|ROM

= Screenshots =

<gallery>
Image:Roman10-system.jpg‎|System menu
Image:Roman10-show_rsx.jpg|Show RSX commands
Image:Roman10-rom_gen.jpg|ROM generator
Image:Roman10-hauptmenue.jpg|Main menu
Image:Roman10-catalog.jpg|Disc catalog
Image:Roman10-about.jpg|About box
</gallery>

File:Roman10-system.jpg

2013-03-07T21:53:25Z

Octoate: ROMan v1.0 system

ROMan v1.0 system

File:Roman10-show rsx.jpg

2013-03-07T21:53:04Z

Octoate: ROMan v1.0 show RSX commands

ROMan v1.0 show RSX commands

File:Roman10-rom gen.jpg

2013-03-07T21:52:45Z

Octoate: ROMan v1.0 ROM generator

ROMan v1.0 ROM generator

File:Roman10-hauptmenue.jpg

2013-03-07T21:52:21Z

Octoate: ROMan v1.0 main menu

ROMan v1.0 main menu

File:Roman10-catalog.jpg

2013-03-07T21:52:00Z

Octoate: ROMan v1.0 Disc catalog

ROMan v1.0 Disc catalog

File:Roman10-about.jpg

2013-03-07T21:51:31Z

Octoate: ROMan v1.0 About Box

ROMan v1.0 About Box

Amstrad CSD

2012-07-25T11:49:16Z

Octoate: added pictures and categories

The Amstrad CSD was a machine that was in-store to demonstrate the hardware of the Amstrad plus.

It had a system cartridge which contained a menu, and could hold a furthur 12 cartridges.

It has additional hardware to allow switching of cartridges.

==Technical==

The information was derived from the software. It is not completely accurate.
Lots of information is not known at this time.

It uses ports fbe0-fbe3. The exact decoding of these ports is unknown.

fbe0 is read only it seems
bits 7..4 seem to be related to the dip switches on the CSD
bit 7 seems to be fixed to GND/0v.
bit 6,5 is the timer value. It is the time allowed between choosing next cartridge to play.
bit 6, bit 5

off off = 8 1 1
off on = 16 1 0
on off = 24 0 1
on on = 32 0 0

bit 4 seems to be timer on/off for time limited play.
fbe0 bits 3..0 are defined by the dial
bit 3 is ignored.

0 = forever?
1 = 8s,
2 = 56s

fbe2 is read only it seems
bits 7..3 are the currently selected cartridge
bits 3..0 ???

fbe1 is writeable
bits 7,6: ???
bits 5..0: are cartridge number??

fbe3 is writeable:
bits 7..4: are cartridge number
bits 3..0: ???

== Pictures ==

<gallery caption="Some photos of Amstrad Expo 90">
Image:csdscreen1.jpg
Image:csdscreen2.jpg
Image:csdface.jpg
Image:csddaughter.jpg
</gallery>

Courtesy of Amstrad.cpc.free.fr

[[Category:Hardware]][[Category:CPC Plus]]