This brings back memories. My first experience of a computer was using a PET 3016 at secondary school in the UK in 1979. Later I bought a Commodore 64 and built

This brings back memories. My first experience of a computer was using a PET 3016 at secondary school in the UK in 1979. Later I bought a Commodore 64 and built an RS232 interface for it - I still have the prototype on stripboard kicking around somewhere. I also wrote a VT100/220 terminal and file transfer program in assembler; it ran in graphics mode, using a custom bitmap font table to create an 80x25 display. Like this PET version, my C64 code had to bitbang the serial interface and because the 'serial port' shared an interrupt with the printer's, when you printed, serial comms was held up and so characters could be lost. I all-but cracked that problem with some clever buffering.