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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.

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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 (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 wide period range (use with bit 6; channel 2 becomes inaccessible)
    • Bit 3: Join channels 3 and 4 for wide period range (use with bit 5; channel 4 becomes inaccessible)
    • Bit 2: High-pass filter (channels 1 and 3, filtered output on channel 1)
    • Bit 1: High-pass filter (channels 2 and 4, filtered output on channel 2)
    • Bit 0: 15KHz mode
  • 12xx: Toggle two-tone mode
    • When enabled, channel 2 modulates channel 1 in an oscillator sync-like manner
    • Only on ASAP core

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Channel Status

When two channels are joined for filtered output, the channel bar shows filter on a bracket tying them together. When two channels are joined for wide period range, the channel bar shows 16-bit on a bracket tying them together.

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ROM Export

A song can be exported as SAP-R, a compressed register dump. More details are available (in Polish) at the Atariki wiki.

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Chip Configuration

PAL: Run the chip at PAL clock (1.77MHz) instead of NTSC (1.79MHz)

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