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Circuitbenders Forum => Circuitbending discussion => Drum machines => Topic started by: julianw on June 12, 2010, 06:43:47 PM

Title: Cheetah MD-16 Custom Sound ROMs
Post by: julianw on June 12, 2010, 06:43:47 PM

Hello everybody,

I'm trying to burn my own drum sounds onto my Cheetah MD-16.

The sounds are stored on 2 x 40pin Fujistsu MB834200A 4mbit (512kb) mask ROMs

After doing a little research looking at the Cheetah datasheet it seems that the M27C400 EPROM is a direct replacement.

I went and bought a 16bit adaptor for my Willem GQ-4X programmer and read out the EPROMs (telling the software that the chip was a M27C400). After opening them in Soundforge and fiddling with the RAW import settings I got a fairly decent waveform, which obviously is lots of drums one after another. (Setting was 16bit PCM/Signed/Little Endian-Intel) None of the other settings/samplerate/bitrates worked - I tried for ages.

The drum sounds are there but they are very distorted, and all digitally messed up, I just wondered if anyone here could help decipher what is going on here, or give some pointers on how to decode these sounds, and encode my own.

I have zipped up the binary images from the 2 Sound ROMs and uploaded them to Mediafire - In case anybody fancys having a crack at decoding them.

http://www.mediafire.com/?qjiqhmd42mb (http://www.mediafire.com/?qjiqhmd42mb)

Thanks in advance for any help guys.
Julian

Title: Re: Cheetah MD-16 Custom Sound ROMs
Post by: Gordonjcp on June 15, 2010, 07:29:51 AM

I'll take a look at this tonight, or possibly a bit later in the week depending on how much stuff has stacked up at work while I was on holiday ;-)

Title: Re: Cheetah MD-16 Custom Sound ROMs
Post by: julianw on December 19, 2012, 12:02:15 AM

I'm really keen to get my own sounds on the MD-16, if Gordon or anyone here can tell me what is going on with the encoding of the sounds I would be most grateful.

The links above are dead so here are new ones.

RAW binaries:
https://dl.dropbox.com/u/51205875/MD16SoundROMs.zip

Here are links to WAVs of the two EPROMs decoded with the above settings so you can listen to what they sound like and hear what I mean.

https://dl.dropbox.com/u/51205875/back.wav
https://dl.dropbox.com/u/51205875/front.wav

Title: Re: Cheetah MD-16 Custom Sound ROMs
Post by: bernie on October 04, 2016, 10:04:17 AM

I still wonder about this. Anyone ever made any progress or have an idea what would require in order to make this possible? Looking at the schematics there is a 16bit dac and a 8bit dac? and the ''output'' bus lines look a bit scrambled.
I just ran the machine with only one rom installed. it looks like some sounds are (completely) there and some might be interleaved with the other rom?? (hence maybe the 8bit dac or maybe not i'm a noob).

I hope the pulled roms in this post are scrambled due to the scrambled pin configuration.
Any knowledge on this would be really appreciated.

Thank you