Hacking JD-800 wavetable?

[Jeroen Proveniers]

> I recently got a Roland JD-800 keyboard and service manual.
> 
> The manual shows the PCM wavetables as 3 x 8 megabit mask 
> ROMs. It should be
> possible to replace the wavetable with 3 x 27C8001 EPROMs but 
> I have been
> unable to figure out the PCM encoding scheme used in the wavetable.
> Anybody have any information on this? My purpose is not to take their
> wavetable, but to put my own in. I love the prettiness of 
> this unit, but I
> want to put in more strange loops and other wavetables.
> 
> Does Roland have a proprietary encoding scheme, and are there 
> any software
> utilities (perhaps for the S-50) that move between open .wav 

Maybe the wavetable format is logarithmic. With 8 bit log you get 13 bits
linear. Have  you already tried soldering one out, reading it with eprom
programmer, and just read the file into a sample editor? You must also know
the headers at the beginning of the rom, sample, etc. to do this
successfully.

JJ