Show HN: 8-bit Sounds – Studio2600 for the VCS (Atari 2600)

Re:Show HN: 8-bit Sounds – Studio2600 for the VCS (Atari 2600) by Lerc on Monday April 30, 2018 @01:29AM (#16956016)

The description of some of the tones is a bit cryptic.

I'd be interested in a deeper explanation of div 15 -> 4 bit poly and 5 bit poly -> 4 bit poly

I'm making a fantasy console, so I ended up spending quite a bit of time designing my own 8 bytes to describe a full range of tone/freq/volume/envelope/bend. Packing expressiveness into a limited number of bits is quite a fun game.

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Re:Show HN: 8-bit Sounds – Studio2600 for the VCS (Atari 2600) by masswerk on Monday April 30, 2018 @03:25AM (#16956497)

The "TIA-1A Hardware Manual" [1] states: "This circuit contains a nine bit shift counter which may be controlled by the output code from a four bit audio control register (AUDC), and is clocked by the frequency select circuit. The control register can be loaded by the micro- processor at any time, and selects different shift counter feedback taps and count lengths to produce a variety of noise and tone qualities."

[1] https://www.atariarchives.org/dev/tia/

There is an "about 30KHz" base frequency, so "div 15" suggests a 2KHz waveform; "4 bit poly" and "5 bit poly" are probably two of the "feedback taps", "and" a logical multiplication of these signals. But this is just my interpretation.

[Edit] For technical details see: https://alienbill.com/2600/cookbook/music/stolberg.txt

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