Vintage Simmons Drums (UK) Users Group

On Mon, 2009-04-20 at 13:58 +0000, Simmons_Drums@yahoogroups.com wrote:

> 1a. Eproms
>     Posted by: "blacklodgeed" edrose1@... blacklodgeed
>     Date: Mon Apr 20, 2009 6:32 am ((PDT))
> 
> I need to buy eproms to burn for my SDS 7. I know I'm looking for
> 2764's and 27128's but there seem to be differences within those types
> of eproms. What do I need to look for and what should I avoid?
> Thanks in advance.
> Ed

Makes no difference to the SDS-7, as long as it's got the right number
of pins.  Where it does make a difference is in programming - typically
a 27C128 will require 12.5V programming rather than 21V programming, but
your programmer should take care of this for you.  On some cheap crappy
programmers like my Willem PCB3 there's a jumper to set, for the
voltage.

You can even use 27C256 and 27C512 EPROMs which are usually cheaper -
either ground the extra pins or blow two or four samples in and select
which one by grounding the unused pin (add a 1k pullup resistor to 5v to
avoid weird glitches).

Gordon