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Last modified on 13 January 2010, at 16:08

Amdrum

Revision as of 16:08, 13 January 2010 by Nocash (Talk | contribs) (→‎Partial dissassembly of player)

Company logo
Box and Manual for the Amdrum

A drumkit by the British company Cheetah.

The drumkit was able to play 8bit sound samples.

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 CPC emulator supports the Amdrum. To hear 'Amdrum' in action the Spectrum emulator Spectaculator emulates the 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).
  • 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:

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)

Partial dissassembly of player

exx     
ld      a,(bc)
add     a,(hl)
ex      de,hl
add     a,(hl)
inc     hl
ex      de,hl
inc     bc
add     a,80h
inc     hl
exx     
out     (c),a
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

ld      b,0ffh
nop     
nop     
nop     
exx     
ld      a,(bc)
add     a,(hl)
ex      de,hl
add     a,(hl)
inc     hl
ex      de,hl
inc     bc
add     a,80h
inc     hl
exx     
out     (c),a     ;out [FFxxh] with xx=garbage (above PIO Port C value)

Kits

Afro Kit Covertape

  • Afro Kit Covertape - Instructions

  • Afro Kit Covertape

  • Afro Kit Instructions

  • Afro Kit Errata

Electro Kit Covertape

  • Electro Kit Covertape - Instructions

  • Electro Kit Covertape

  • Electro Kit Instructions

Latin Kit Covertape

  • Latin Kit Covertape - Instructions

  • Latin Kit Covertape

  • Latin Kit Instructions

Tapes

Amdrum Tape

  • Amdrum Tape

  • Amdrum Tape side A

  • Amdrum Tape side B

Afro Kit Tape

  • Afro Kit Tape

  • Afro Kit Tape side A

  • Afro Kit Tape side B

Electro Kit Tape

  • Electro Kit Tape

  • Electro Kit Tape side A

  • Electro Kit Tape side B

Latin Kit Tape

  • Latin Kit Tape

  • Latin Kit Tape side A

  • Latin Kit Tape side B

Pictures

  • AMDRUM
  • Amdrum1.jpg
  • Amdrum2.jpg

  • Component side

  • "AMSTRAD SPECDRUM"

  • Screen shot

  • Screen shot

  • Box

  • Amdrum inside box

Manual

Reviews / Commercials

Weblinks

Site about the SpecDrum

Review of the Spectrum version

Another review

Other playback devices

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