I used to sell them via eBay and have a couple dozen 27C256 chips left over. If you'd like one programmed, you can send a few bucks to cover mailing. Be sure of what you need first. The change to 27C256 compatible systems happened during serial numbers beginning with 311. You can check the motherboard number, but the easiest way for me is the check the original ROM. Systems with the Sharp ROM are not compatible with the 27C256 IC; see 1. below.
1. The early M100 (with a Sharp ROM IC) requires an adapter PCB. Solder everything to the adapter and plug it in. Read about the Mike Stein adapter here: http://bitchin100.com/wiki/index.php?title=M100ROM You can buy it here: https://www.oshpark.com/shared_projects/Kil9S1ya 2. The later Model 100 (not a Sharp IC) can accept the 27C256 in the socket. You get a Y2K IC, pull out the old ROM, push in the new ROM, and (hard) reset. 3. The Model 102, such as I have, is compatible with the 27C256, but the original ROM is soldered into the motherboard. It must be removed before installing a new IC. I use a set of SIP machined female headers to create a socket for the 27C256 that is similar to the RAM module sockets. Anything else would be too tall for the space available inside the closed case. I plug a 28 pin socket into the two headers to keep them aligned while soldering. Things are a bit close and if you are not careful, you end up -- like me, with a dead M102. God blees, GregS <><
