My first was a homebrew of my own design hand wire-wrapped on perfboard. Components were a Signetics 2650A CPU, 6KB of 2114 (1024x4bit) static ram, and a handfu

My first was a homebrew of my own design hand wire-wrapped on perfboard. Components were a Signetics 2650A CPU, 6KB of 2114 (1024x4bit) static ram, and a handful of 7400L series TTL glue logic. I got most of the parts from salvage or donations. Someone burned me a 2KB eprom copy of the Signetics rom monitor and into memory assembler. As that did not include documentation I wrote a disassembler in FORTRAN using works Univac 1108. The first time I hooked it up it did nothing, but replacing the RC oscillator with a proper crystal for the clock fixed it. Serial IO was bit banged in software at 110 baud to a Teletype ASR 33. The RC clock was not good enough to sync the serial rate. Programs could be typed directly into memory a line at a time or read/punched from/to paper tape. It took months, but I was poor and a pre-built computer would have cost thousands. I never really used it for much, but I did learn a bunch about digital logic, assembler programming, hardware and software debugging etc. Probably the most educational thing I ever did. I remember many evenings sitting up in bed wire-wrapping, quite content except that my girl friend complained about the tiny itchy bits of insulation stripped from the wire ends getting into the sheets.