RCA Cosmac VIP System
The RCA COSMAC VIP system had 4K of memory with a Super Sound board plugged-in. Each Super Sound board yields two separate sound channels. The music is implemented with a program called PIN-8, (Play it Now) written by Joe Welsbecker, who also designed the Super Sound board. Music is encoded from sheet music with note pitch and duration being described with a single 8-bit byte. PIN-8 is structured so that unique measures need only to be encoded once and can be used in any sequence. The amplitude envelope of a note can be controlled to have one of 16 values for each of 16 time segments of a note's duration.
The program is interrupt-driven and the determining interrupt signal defines the tempo, which is controlled by the potentiometer on the Super Sound card. It is a simple matter to take the interrupt signal from one VIP system to synchronously drive as many other VIPs as desired. The Bach Fugue uses two VIP systems synchronized together.