The Vectrex uses the AY-3-8912 Programmable Sound Generator (PSG) to produce music and sound effects. You can control the PSG directly from the SmartCart using the Sound() subroutine. Your first source for information on using Sound() should be the Vectrex32 manual, but you can read the original AY-3-8912 documentation here:
- Data Sheet (PDF)
- Manual (PDF)