a computer from 1977 which was leader on US schools back then. subsequently the Apple II took its throne.
maybe no better than a computer terminal, but somebody discovered a way to update the screen at turbo rate - and eventually its sound "chip" (it was nothing more than an 8-bit shift register) was abused as well.
some of these didn't even have sound...
10xx: set waveform.xxis a bitmask.
this chip uses the PET instrument editor.