Vintage Simmons Drums (UK) Users Group

superwolle70 wrote:
> Hi, before you both bid yourself to death: Michael Buchner has
> developped a way to read, write and edit the eproms with an ordinary
> prommer. The plan is to publish the library (official and home brewed
> stuff) as prommable binary files together with a "cookbook". Probably
> on my site. 

Well, I've just got a load of EPROM images from Paul Maddox.  Now all I 
need to do is wait until my friend comes back from Ireland so I can go 
and steal his EPROM programmer.

There's nothing particularly magic about the contents of the EPROMs. 
It's just an unsigned 8-bit sample, the size of the available space. 
Nothing else.

You could make a very simple Simmons ROM player (well actually, it would 
play any similar chip, probably Sequential Drumtrak ones too) by just 
having a 13- or 14-bit counter clocked at a few kHz (anywhere from, say, 
6kHz to 40kHz) attached to the address lines, and an R-2R ladder 
(rembember building your own Covox Speech Thing from the plans 
downloaded off a bulletin board, way back before sound cards were 
common?).  Then to trigger the sample, you'd just drop the reset pin on 
the counter, it would count up, and the sample would play through the 
simple D/A converter.

Add a simple "decay" circuit, and have it control the clock speed, and a 
trigger circuit to control the counter and decay envelope, and 
congratulations - you've just invented the SDS-1!

Gordon.