--- In tr-707@yahoogroups.com , "acousmatique" <acousmatique@y...> wrote:

> 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.

Poking further, it seems that one of the reasons why the 61256 was never
very popular was because it was soon superceded by the 62256. Also a 32k
X 8 SRAM. Main diff is spozedly faster access time, but I don't have info on the
specs of either ic. This is very kewl because there are quite a few EPROM
programmers out there which can write to these!

The next issue then is: what sort of addressing As to say, how many
kilobytes per sound I may find the info in the service manual, need to go over
it again.

For those who may be interested in redoing Olde Schoole sample-based
drum machines, today I found a site with lots of useful info- but not about the
707, rather the Oberheim DMX. This is good, as there are few sources of good
info about TR-707 drum internals. This info is very similar, since the ROMpler
workings are typical stuph.
< http://www.electrongate.com/dmxfiles/index.html >

Very interesting about the above site, the author - Paul J White- has written a
few little DOS apps for these sorts of activities. "WAV2DMX" and "DWAV" can
respectively write sounds to, or read sounds from, EPROMs. He even
includes source code for DWAV, so it might be modifyable for ripping TR-707
SRAM contents.

Once I know how the drum sounds are layed out in memory, I can put some
new ones! CJ