[Oliver] has developed A2Pico. It’s a series of Apple II peripheral cards that are based around the Raspberry Pi Pico, as you might have guessed. [Oliver] has been working in the area since 2021 ...

Using an 8-bit 6502 microprocessor running at 1 MHz and an 8-bit bus, it ran the Apple DOS and ProDOS operating systems. AppleSoft BASIC ... time (see CPM). Apple II, II Plus, IIe and IIc ...

With the card installed in Slot 7 of the Apple II and the DAC wired through to the synth’s CV/gate, it’s then a trivial matter of writing POKE statements in Applesoft BASIC to control the synth.

An early version of the BASIC programming language from Apple that came with the Apple II. Installed in firmware and always available, it was the successor to Integer BASIC. See Integer BASIC.