Amdrum

2021-04-28T18:33:45Z

Pianoplonker:

[[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")

Aside of Cheetahs own sequencer you can use some commands of the RSX ROM for LambdaSpeak III to use the Amdrum.

Now, thanks to Jose Leandro, the hardware specialist of the spectrum, with his famous page :

http://trastero.speccy.org/cosas/JL/JL.htm

We can know more about this hardware.

== 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||Charge pump circuit, used to create negative voltage rail for the op amp
|-
|TL064CDP||Quad Operational Amplifier||Buffer and low pass filter
|-
|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)

== Pictures ==

<gallery caption="AMDRUM">

Image:Amdrum_1.jpg|Box
Image:Amdrum_2.jpg|Amdrum inside box
Image:Amdrum screen shot 1.gif|Screen shot
Image:Amdrum screen shot 2.gif|Screen shot

</gallery>

<gallery caption="300dpi scans by Robcfg">

Image:AMDRUM_PCB_Top.jpg|PCB Top
Image:AMDRUM_PCB_Bottom.jpg|PCB Bottom
Image:AMDRUM_Top.jpg|Interface Top
Image:AMDRUM_Bottom.jpg|Interface Bottom

</gallery>

<gallery caption="Amdrum Layout, thanks to Jose Leandro">

File:Amdrum - interface_delante.jpg|Amdrum - Front Box
File:Amdrum - interface_detras.jpg|Amdrum - Back Box
File:Amdrum - cara_componentes.jpg|Amdrum - Components
File:Amdrum - cara_pistas.jpg|Amdrum - Tracks
File:Amdrum PCB.png|Amdrum - PCB Front
File:Amdrum Layout.png|Amdrum - Layout

</gallery>

== 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>

== 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>

== Kits ==

{| class="wikitable sortable" style="width:100%"
|''Title''||''Front Covertape''||''Back Covertape''||''Tape Side A''||''Tape Side B''
|-
|[[Afro Kit]]||[[Image:Afro Kit 1.jpg|120px]]||[[Image:Afro Kit 2.jpg|120px]]||[[Image:Afro Kit Tape A.jpg|120px]]||[[Image:Afro Kit Tape B.jpg|120px]]
|-
|[[Electro Kit]]||[[Image:Electro Kit 1.jpg|120px]]||[[Image:Electro Kit 2.jpg|120px]]||[[Image:Electro Kit Tape A.jpg|120px]]||[[Image:Electro Kit Tape B.jpg|120px]]
|-
|[[Latin Kit]]||[[Image:Latin Kit 1.jpg|120px]]||[[Image:Latin Kit 2.jpg|120px]]||[[Image:Latin Kit Tape A.jpg|120px]]||[[Image:Latin Kit Tape B.jpg|120px]]
|-
|}

<gallery caption="Afro Kit - Errata">

Image:Afro Kit Errata.jpg|Afro Kit Errata

</gallery>

== 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}}

== Manual ==

* [[Media:Amdrum Manual.pdf|Amdrum (Cheetah) Manual]] {{EN}} {{PDF}}

== 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)

* [[Media:Amdrum (Eagle).zip|Amdrum (Eagle).zip]] (Amdrum files for Eagle)

== Weblinks ==

* [http://www.cpc-power.com/index.php?page=detail&num=4294 ''Amdrum'' from CPC-Power]
* [http://www.cpc-power.com/index.php?page=detail&num=4312 ''Amdrum Afro kit'' from CPC-Power]
* [http://www.cpc-power.com/index.php?page=detail&num=4313 ''Amdrum Electro kit'' from CPC-Power]
* [http://www.cpc-power.com/index.php?page=detail&num=4311 ''Amdrum Latin kit'' from CPC-Power]
* [https://cpcrulez.fr/hardware-audio-amdrum_AA.htm ''Amdrum'' from CPCrulez]
* [http://hardware.speccy.org/temp/Amstrad-Amdrum.html ''Amdrum'' from hardware.speccy.org]
* [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 Spectrum review]

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

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Amdrum