Synthpopalooza Posted September 18, 2013 Share Posted September 18, 2013 (edited) When doing the music for Pac-Man Plus's Bentley Bear game, I noticed there was scant little documentation for the frequency settings for all of the possible distortions in POKEY. I sat down at it, and compiled a note table that might be helpful to those using the POKEY for music. There is a text doc file, and an excel sheet which also shows the hex values. Values are for these distortion settings: Distortion 10 (AUDCx=$A0 - $AF) ... square wave, pure tones. Distortion 2 (AUDCX=$20 - $2F) ... triangle wave, bell tones. Distortion 12a (AUDCx=$C0 - $CF) ... sawtooth wave, buzzy tones Distortion 12b (AUDCx=$c0 - $CF) ... sawtooth wave, non-buzzy tones 12b is different from 12a, in that you only use frequencies for AUDFx that are divisible by 3. This produces smoother tones than other frequency settings. The bass in Donkey Kong XM uses this method. Settings are for 8-bit and 16-bit mode. 8-bit mode uses AUDCTL=$00 When using 8-bit mode, tuning errors will increase as you get into higher frequencies. 16-bit mode uses AUDCTL=$50 or $28 ... 1.79 mhz clock, with either channels 1+2, or 3+4 joined. When joining channels, the first AUDC register is zeroed, and the second is used to set the control and volume. the two AUDF registers use the 16-bit frequency value in a low-order and high-order format respectively. I used this method in the Bentley Bear game for the bass track in the title music, and the level complete music. On distortions 12a and 12b, tuning errors will also increase as you get into higher frequencies. All of these settings were tuned by ear, using the distortion 10 table located here, as a reference: http://www.atarimagazines.com/compute/issue34/112_1_16-BIT_ATARI_MUSIC.php I hope these prove useful. Enjoy! If anyone could double check my work, and proofread it, make sure it works ok, I'd appreciate it! pokey notes.xls pokey note table.txt Edited July 24, 2019 by Synthpopalooza Correction of AUDCTL settings 8 2 Quote Link to comment Share on other sites More sharing options...
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