I was just looking through the reprint of the Radio-Electronic magazines articles that describe the Simon computer. For those of you who haven't seen them and have thought about building one, they are NOT a construction or kit article per se, but rather they give a description of how the computer works. As such, I don't consider it "light reading" material to just read and build! It doesn't look like it would be too difficult to build once the wiring was laid out. The 120 or so relays used were war surplus, 24 VDC, 4PDT according to the article. The only perhaps hard to find items would be the stepper switch with make-before-break contacts, and a paper tape reader. One perverted thought I've had to make things a lot simpler to build is to use a PLC :). I started to gather the parts some time ago including 150 NOS DPDT 12 VDC relays and some NOS pilot light housings, but just don't have the time for YAP (Yet Another Project.) So, the parts I've gathered along with a CD containing scans of the Radio-Electronics Simon reprint have been listed on VCM.