#registers
- Game Boy sound hardware (APU) chipThe game-boy 's sound unit, the APU, has four channels that are each built differently — "unlike some other sound chips, such as the C64's SID or the Atari 5200's POKEY, each sound channel is specialized" — plus a VIN …
- C64 Programmer's Reference Guide, ch. 4 — Programming Sound and Music on Your Commodore 64 (1982) summaryThe official 1982 introduction to the sid from the BASIC programmer's side: ten example programs that POKE the chip's registers, each with a line-by-line explanation, plus a short "technical explanation" of frequency, …
- MOS 6581 Sound Interface Device (SID) datasheet — the text behind Appendix O summaryThe manufacturer's twelve-page specification of the sid : block description, the 29-register map, a paragraph per register bit, the envelope rate table, the filter, pins and electrical data, the note table with a …
- Pan Docs — Audio Registers summaryThe register-by-register specification of the game-boy-apu : the NRxy naming scheme (x = channel, 5 = global; NRx1 length/duty, NRx2 volume/envelope, NRx3 period low, NRx4 trigger, length enable and period high), then …