Greetings all …
Psyched to find a group which recognizes the potential of this box.

The ROM is not actually a ROM as such, but SRAM- static-RAM. As you might
have already noticed, it is not a popular ic, nearly no info. Still, the pi=
nouts are
available out there in the service book schemos. Blank chips are available =
at
times from >www.unicornelectronics.com<, but I have found no burners which =

boast supporting these ics. If I could find the chip's data sheets, there m=
ight
be, as there sometimes are, application notes regarding how to program
them.

More challenging is that the sounds are really 6-bits, not the often mentio=
ned
eight! The design of the TR-707 is tricky/cheap/elegant... Roland did not w=
ant
to shell out cash for (then pricey) DACs, so they used extreme com-pansion =

on the 6-bit sounds, making them sound more full by means of analog
envelopes. If I recall, the DACs are resistor array types. Just how is the =
sound
encoded on there I don't know. If I had a more digital workbench here, I'd=
like
to try to clock the data out under controlled conditions, and analyze it. M=
aybe
try to "reconstitute" it in SoundHack. I probably will someday.

Probably much simpler.... A year ago I was pondering the 707 voice chips,
and was wondering whether or not there were any adaptors for using the
intel-style EPROMs, which are cheep, plentiful, and supported by every
burner. I did (after many hours of searching) the page of a person who had =

made adaptor sockets for the 707, and had burned new EPROMS for it. I have =

been trying to relocate that info recently with no luck. I might have trans=
cribed
the info in my thousands of pages of hardcopy notes, or archived the page o=
n
a cd. The adaptor was quite simple, might have even just been to make the
functions of the EPROM pins correspond to where the SRAMs are. I will
(eventually) find the info.

Meanwhile, there are those analog envelopes to play with. I have yet to do =
so,
since my bench is full (Tama Techstar drum circuits!), and I've got my new =
1
month-old son needing much of my time. Combining the clock-rate control of =

the "kick" with a knob to very the envelope decay sounds like a fun mod to =
try.

Of course, any "computer person" who has experience with SRAM could
probably do many fun things by clocking new voices out of a big chunk of
SRAM, a la sampler. Beyond my scope for now.

I will try to find that chip substitution info
CJ