In the late 1970s, my dad purchased an S-100 bus computer from Thinker Toys for about $3,000 (would be close to $15,000 today after adjusting for inflation). It had a Z80 microprocessor and ran CP/M. As was true of many hobbyist computers from this era, it came with full source code (in beautifully documented assembly) both for CP/M and for the BIOS. This was important because if you wanted to add peripherals or make other modifications to your computer, you had to edit the source code and recompile the BIOS.

A few years later my dad decided to buy an Epson MX-80 for his computer. The daisy-wheel and the plotter at work (he worked at SRI) just didn't cut it, I guess? This required buying a serial card for the S-100. In order to get that printer to work, he had to first, wire up a cable because the data lines from the card were on different pins in the printer. I believe there was a version of the MX-80 that came with a serial port instead of a parallel port which made some things easier. I was recruited as his assistant. Then he had to modify and recompile the BIOS. Then he had to also make some changes to CP/M. This was a process of trial and error that lasted for weeks. I remember I was away at summer camp and he sent me a letter he printed out on that printer. He was so happy that he finally got it to work.

Anyways, this resurfaced that memory and I thought I might as well share it. I still have the printout he sent me somewhere.