View source for Amdrum

[[Image:cheetah logo.jpg|right|thumb|250px|Company logo]]
[[Image:Amdrum.JPG|thumb|250px|Box and Manual for the Amdrum]]

The Amdrum is a 8bit D/A converter (hardware) with drumkit (software), made by the British company [[Cheetah]].

Quality of the playback was nice, considering the time and price.

The samples were read from the suplied tapes.

There were serveral tapes with different themes.

Along with the Amdrum came a sequencing program.

It was possible to copy the samples to disc, but the sequencing program had to be patched!

Amdrum was probably Cheetahs version of the SpecDrum (As revealed on the PCB "AMSTRAD SPECDRUM")

No other software than Cheetahs own sequencer is know to use the Amdrum.

== Technical Specifications ==

* Uses I/O Port FFxxh (Write only), ie. only /IORQ, /WR, A15-A8 are decoded. A7..A0 are not decoded, and /RD isn't used, too.
* Port usage: Write 8bit unsigned sample data to Port FFxxh. The D/A converter is mono and has only one channel (mixing multiple channels is to be done by software).
* After booting, the Amdrum software first sets port [FF80h]=80h. Emulators can use that feature to detect Amdrum software - and, after [FF80h]=80h was detected, map the whole range of ports FF00h..FFFFh to the Amdrum.
* During operation, the Amdrum software uses port FFxxh. Where "xx" is garbage coming from the Amdrums keyboard scanning routine (see disassembly below).

The five chips on the single-sided PCB are:

{|{{Prettytable|width: 700px; font-size: 2em;}}
|74LS30N||Single 8-input NAND||Port decoding, /ADDR_MATCH=LOW when A8..A15 all HIGH
|-
|74LS32N||Quad 2-input OR||Port decoding, /DAC_WRITE when /ADDR_MATCH, /IORQ, /WR all LOW
|-
|SN74LS04N||Hex Inverters||purpose unknown? (used in the analog part, not for Port decoding)
|-
|TL064CDP||Quad Amplifier||no info how the 4 amplifier stages are used?
|-
|Ferranti ZN428E-8||8bit DAC||mono one-channel 8bit D/A converter (unsigned samples)
|}

* [[Media:ZN428.pdf|ZN428 Datasheet]] - 8bit D/A Converter
* [[Media:TL064.pdf|TL064 Datasheet]] - Quad Amplifier

== Partial dissassembly of player ==
 exx     
 ld      a,(bc)    ;get channel 1
 add     a,(hl)    ;add channel 2
 ex      de,hl
 add     a,(hl)    ;add channel 3
 inc     hl
 ex      de,hl
 inc     bc
 add     a,80h     ;add bias (signed to unsigned)
 inc     hl
 exx     
 out     (c),a     ;out [FFxxh] with C=whatever
 ld      b,0f6h
 in      a,(c)
 ld      c,a       ;C=PIO Port C (keyb row, tape, psg control)
 xor     05h   ;five ???
 out     (c),a
 ld      a,0f4h
 in      a,(66h)
 ld      (404eh),a
 out     (c),c
 ...           ;something missing here?
 ld      b,0ffh
 nop     
 nop     
 nop     
 exx     
 ld      a,(bc)    ;get channel 1
 add     a,(hl)    ;add channel 2
 ex      de,hl
 add     a,(hl)    ;add channel 3
 inc     hl
 ex      de,hl
 inc     bc
 add     a,80h     ;add bias (signed to unsigned)
 inc     hl
 exx     
 out     (c),a     ;out [FFxxh] with xx=garbage (above PIO Port C value)

== Kits ==

=== Afro Kit Covertape ===

<gallery caption="Afro Kit Covertape - Instructions">

Image:Afro Kit 1.jpg|Afro Kit Covertape
Image:Afro Kit 2.jpg|Afro Kit Instructions
Image:Afro Kit Errata.jpg|Afro Kit Errata

</gallery>

=== Electro Kit Covertape ===

<gallery caption="Electro Kit Covertape - Instructions">

Image:Electro Kit 1.jpg|Electro Kit Covertape
Image:Electro Kit 2.jpg|Electro Kit Instructions

</gallery>

=== Latin Kit Covertape ===

<gallery caption="Latin Kit Covertape - Instructions">

Image:Latin Kit 1.jpg|Latin Kit Covertape
Image:Latin Kit 2.jpg|Latin Kit Instructions

</gallery>

== Tapes ==

=== Amdrum Tape ===

<gallery caption="Amdrum Tape">

Image:Amdrum Tape A.jpg|Amdrum Tape side A
Image:Amdrum Tape B.jpg|Amdrum Tape side B

</gallery>

=== Afro Kit Tape ===

<gallery caption="Afro Kit Tape">

Image:Afro Kit Tape A.jpg|Afro Kit Tape side A
Image:Afro Kit Tape B.jpg|Afro Kit Tape side B

</gallery>

=== Electro Kit Tape ===

<gallery caption="Electro Kit Tape">

Image:Electro Kit Tape A.jpg|Electro Kit Tape side A
Image:Electro Kit Tape B.jpg|Electro Kit Tape side B

</gallery>

=== Latin Kit Tape ===

<gallery caption="Latin Kit Tape">

Image:Latin Kit Tape A.jpg|Latin Kit Tape side A
Image:Latin Kit Tape B.jpg|Latin Kit Tape side B

</gallery>

== Pictures ==

<gallery caption="AMDRUM">
Image:Amdrum1.jpg|
Image:Amdrum2.jpg|
Image:Amdrum inside1.jpg|Component side
Image:Amdrum inside2.jpg|"AMSTRAD SPECDRUM"
Image:Amdrum screen shot 1.gif|Screen shot
Image:Amdrum screen shot 2.gif|Screen shot
Image:Amdrum_1.jpg|Box
Image:Amdrum_2.jpg|Amdrum inside box
</gallery>

<gallery caption="AMDRUM 300dpi scans">
Image:AMDRUM_Top.jpg|Interface Top
Image:AMDRUM_Bottom.jpg|Interface Bottom
Image:AMDRUM_PCB_Top.jpg|PCB Top
Image:AMDRUM_PCB_Bottom.jpg|PCB Bottom
</gallery>

== Manual ==

* [[Media:Amdrum Manual.pdf|Amdrum Manual]] (pdf)

== Reviews / Commercials ==

<gallery caption="Commercials for the Amdrum">
Image:amdrum commercial.jpg|Commercial for Amdrum
Image:Amstrad Computer User8610028.jpg|Review of the Amdrum in [[Amstrad Computer User]]
Image:Amstrad Computer User8610029.jpg
Image:Amstrad Computer User8610030.jpg
</gallery>

== Weblinks ==

[http://www.engadget.com/2005/10/28/music-thing-the-zx-spectrum-specdrum-module/ Site about the SpecDrum]

[http://www.crashonline.org.uk/27/specdrum.htm Review of the Spectrum version]

[http://www.worldofspectrum.org/hardware/feat42.html Another review]

== Other playback devices ==

* [[Digiblaster]] (DIY) (8bit DAC on printer port)
* [[Music Machine]]

== Videos ==

AmDrum on Amstrad CPC (emulated with JavaCPC)

{{#ev:youtube|0z-jGDOzwGQ|400}}

A presentation(from around 1985) of the ZX Spectrum version of the Amdrum(Specdrum), also mention of the upcomming Amstrad CPC version

{{#ev:youtube|m6R_W9CZWGU|400}}

== Download ==

* [[Media:Amdrum.zip|Amdrum.zip]] (CDT for Emulators)
* [[Media:Amdrum Afro Kit.zip|Amdrum Afro Kit.zip]] (CDT for Emulators)
* [[Media:Amdrum Electro Kit.zip|Amdrum Electro Kit.zip]] (CDT for Emulators)
* [[Media:Amdrum Latin Kit.zip|Amdrum Latin Kit.zip]] (CDT for Emulators)

== Links ==

* [http://www.cpc-power.com/index.php?page=detail&num=4294 CPC game base from CPC Power] (Amdrum)
* [http://www.cpc-power.com/index.php?page=detail&num=4312 CPC game base from CPC Power] (Amdrum Afro kit)
* [http://www.cpc-power.com/index.php?page=detail&num=4313 CPC game base from CPC Power] (Amdrum Electro kit)
* [http://www.cpc-power.com/index.php?page=detail&num=4311 CPC game base from CPC Power] (Amdrum Latin kit)

 [[Category:Peripherals]] [[Category:Music and sound]] [[Category:Manual]][[Category:Video contents]]