Zapple Monitor

The Zapple Monitor was a firmware-based product developed by Roger Amidon ( [http://www.roger.amidon.com/roger.pdf Bio (pdf)] ) at Technical Design Laboratories (also known as "TDL"). TDL was based in Princeton, New Jersey, USA in the 1970s and early 1980s.

The "Zapple" monitor supplied basic input/output services (BIOS) for S-100-based Z-80 computer systems such as the classic Altair and IMSAI S-100 systems.

Pre-dating floppy interfaces and other more familiar mass-storage devices for personal computers, the Zapple multifunction card hosting the firmware monitor included an RS-232 serial interface along with a cassette tape based hardware interface seemingly optimized for a particular portable Sanyo tape deck that many S-100 aficionados at the time held to be the standard of reliability.