Hi ALL! I have this here Imsai EXP-7 backplane from 1977 I thought would make a nice S-100 build but I need more info on it. All I can find is this reference:
“IMSAI offered a terminated motherboard beginning in Spring of 1977 with the introduction of the VDP-80 (Video Display Processor) which used an EXP-7 (7 card slots), and the EXP-10 used in the 80xx and VDP4x series machines. Termination of address and data lines was provided with 220/330 ohm resistors referenced to regulated five volts, a standard industry practice at that time. In 1981, Fischer-Freitas Corporation entered into agreement with Morrow Designs to offer George Morrow’s 20 slot terminated motherboard as an option. We only sold about 20.”
Seems this is a pretty early board by imsai, only two years into their production. Here are photos of the backplane. It has two empty IC sockets. And there are 5 sets of 20 pins on the solder side that look like components used to be there and there are cut traces. I really want to find info on this board so I can do a build using it. Could use all the help I can get.
