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furnace/doc/7-systems/pokey.md
Electric Keet fc3167d610 Grab bag of added documentation.
Casio PV-1000 added, Genesis expanded, sample editor added.
2023-07-03 14:06:00 -07:00

1.4 KiB

POKEY

a sound and input chip developed by Atari for their 8-bit computers (Atari 400, 800, XL/XE and so on). 4 channels of signature Atari sounds.

effects

  • 10xx: set waveform.
    • 0: harsh noise (poly5+17)
    • 1: square buzz (poly5)
    • 2: weird noise (poly4+5)
    • 3: square buzz (poly5)
    • 4: soft noise (poly17)
    • 5: square
    • 6: bass (poly4)
    • 7: buzz (poly4)
  • 11xx: set AUDCTL. xx is a bitmask.
    • bit 7: 9-bit poly mode. shortens noise.
    • bit 6: high channel 1 clock (~1.79MHz on NTSC).
      • overrides 15KHz mode.
    • bit 5: high channel 3 clock (~1.79MHz on NTSC).
      • overrides 15KHz mode.
    • bit 4: join channels 1 and 2 for a wide period range.
      • use with conjunction with bit 6.
      • channel 2 becomes inaccessible when this is on.
    • bit 3: join channels 3 and 4 for a wide period range.
      • use with conjunction with bit 5.
      • channel 4 becomes inaccessible when this is on.
    • bit 2: high-pass filter (channels 1 and 3).
      • filtered output on channel 1 (I suggest you to set channel 3 volume to 0).
      • use for PWM effects (not automatic!).
    • bit 1: high-pass filter (channels 2 and 4).
      • filtered output on channel 2 (I suggest you to set channel 4 volume to 0).
      • use for PWM effects (not automatic!).
    • bit 0: 15KHz mode.
  • 12xx: toggle two-tone mode.
    • when enabled, channel 2 modulates channel 1. I don't know how, but it does.
    • only on ASAP core.