Difference between revisions of "Amdrum"
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* 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). | * 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. The playback routine also scans the keyboard. The lower 8-bits of the I/O port come from the last value of the C register used to scan the keyboard. | * The Amdrum software uses port FFxxh. The playback routine also scans the keyboard. The lower 8-bits of the I/O port come from the last value of the C register used to scan the keyboard. | ||
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The five chips on the single-sided PCB are: | The five chips on the single-sided PCB are: | ||
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* [[Media:ZN428.pdf|ZN428 Datasheet]] - 8bit D/A Converter | * [[Media:ZN428.pdf|ZN428 Datasheet]] - 8bit D/A Converter | ||
* [[Media:TL064.pdf|TL064 Datasheet]] - Quad Amplifier | * [[Media:TL064.pdf|TL064 Datasheet]] - Quad Amplifier | ||
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+ | == 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 | ||
+ | xor 05h | ||
+ | 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 | ||
== Kits == | == Kits == |
Revision as of 15:53, 13 January 2010
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.
Contents
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. The playback routine also scans the keyboard. The lower 8-bits of the I/O port come from the last value of the C register used to scan the keyboard.
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) |
- ZN428 Datasheet - 8bit D/A Converter
- TL064 Datasheet - Quad Amplifier
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 xor 05h 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
Kits
Afro Kit Covertape
Electro Kit Covertape
Latin Kit Covertape
Tapes
Amdrum Tape
Afro Kit Tape
Electro Kit Tape
Latin Kit Tape
Pictures
Manual
- Amdrum Manual (pdf)
Reviews / Commercials
Review of the Amdrum in Amstrad Computer User
Weblinks
Review of the Spectrum version
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
- Amdrum.zip (CDT for Emulators)
- Amdrum Afro Kit.zip (CDT for Emulators)
- Amdrum Electro Kit.zip (CDT for Emulators)
- Amdrum Latin Kit.zip (CDT for Emulators)