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[[Image:Amdrum.JPG|thumb|250px|Box and Manual for the Amdrum]]
[[Image:Amdrum.JPG|thumb|250px|Box and Manual for the Amdrum]]


A drumkit by the British company [[Cheetah]].
The Amdrum is an 8bit D/A converter (hardware) with drumkit (software), made 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 was read from the suplied tapes.
There was 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")
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 ROM|LambdaSpeak III]] to use the Amdrum.


No CPC emulator supports the Amdrum. To hear 'Amdrum' in action the Spectrum emulator Spectaculator emulates the SpecDrum.  
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.


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


== Technical Specifications ==
== Technical Specifications ==


The PCB(oneside) contains five chips:
* 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;}}
{|{{Prettytable|width: 700px; font-size: 2em;}}
|74LS30N||Port decoding  
|74LS30N||Single 8-input NAND||Port decoding, /ADDR_MATCH=LOW when A8..A15 all HIGH
|-
|-
|74LS32N||Port decoding
|74LS32N||Quad 2-input OR||Port decoding, /DAC_WRITE when /ADDR_MATCH, /IORQ, /WR all LOW
|-
|-
|SN74LS04N||?
|SN74LS04N||Hex Inverters||Charge pump circuit, used to create negative voltage rail for the op amp
|-
|-
|064C0P||Amplifier?
|TL064CDP||Quad Operational Amplifier||Buffer and low pass filter
|-
|-
|Ferranti ZN428E-8||8bit DAC
|Ferranti ZN428E-8||8bit DAC||mono one-channel 8bit D/A converter (unsigned samples)
|}
|}


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


== Weblinks ==
== 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)


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


[http://www.crashonline.org.uk/27/specdrum.htm Review of the Spectrum version]
<gallery caption="AMDRUM">


[http://www.worldofspectrum.org/hardware/feat42.html Another review]
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 ==
== Other playback devices ==


[[Music Machine]]
* [[Digiblaster]] (DIY) (8bit DAC on printer port)
* [[Music Machine]]
 
== Videos ==
 
AmDrum on Amstrad CPC (emulated with JavaCPC)


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


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


<gallery caption="The Music Machine">
{{#ev:youtube|m6R_W9CZWGU|400}}
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
</gallery>


== Manual ==
== Manual ==


<gallery caption="Amdrum Manual">
* [[Media:Amdrum Manual.pdf|Amdrum (Cheetah) Manual]] {{EN}} {{PDF}}
Image:Amdrum Manual.pdf| (English)
* [https://framagit.org/offset/amdrum-acepansion Amdrum ACEpansion] on Framagit
</gallery>
 
== 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:Hardware]] [[Category:Peripherals]] [[Category:Music and sound]] [[Category:Manual]]
[[Category:Peripherals]] [[Category:Music and sound]] [[Category:Manual]] [[Category:Video contents]]

Latest revision as of 01:13, 10 April 2025

Error creating thumbnail: Unable to save thumbnail to destination
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Error creating thumbnail: Unable to save thumbnail to destination
Box and Manual for the Amdrum

The Amdrum is an 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:

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)

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

Reviews / Commercials

Amdrum Tape

Kits

Title Front Covertape Back Covertape Tape Side A Tape Side B
Afro Kit Error creating thumbnail: Unable to save thumbnail to destination Error creating thumbnail: Unable to save thumbnail to destination Error creating thumbnail: Unable to save thumbnail to destination Error creating thumbnail: Unable to save thumbnail to destination
Electro Kit Error creating thumbnail: Unable to save thumbnail to destination Error creating thumbnail: Unable to save thumbnail to destination Error creating thumbnail: Unable to save thumbnail to destination Error creating thumbnail: Unable to save thumbnail to destination
Latin Kit Error creating thumbnail: Unable to save thumbnail to destination Error creating thumbnail: Unable to save thumbnail to destination Error creating thumbnail: Unable to save thumbnail to destination Error creating thumbnail: Unable to save thumbnail to destination

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}}

Manual

Download

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