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