Show HN: 8-bit Sounds – Studio2600 for the VCS (Atari 2600)
1–10 of 15 posts
Re: Show HN: 8-bit Sounds – Studio2600 for the VCS (Atari 2600)
#2For a bit of technical background see the project blog (it's about a game): http://www.masswerk.at/rc2018/04/
Re: Show HN: 8-bit Sounds – Studio2600 for the VCS (Atari 2600)
#3Row #3, column #11 is the sound of Lex Luthor's flying propeller backpack in Superman.
Re: Show HN: 8-bit Sounds – Studio2600 for the VCS (Atari 2600)
#4Wow, that's really neat.
I knew the sounds to be wrung from the VCS were quite varied, but they really did hit a pretty good set from pureish tones to heavy distorted noise.
Re: Show HN: 8-bit Sounds – Studio2600 for the VCS (Atari 2600)
#5Fun track based on the 2600 sound set: https://www.youtube.com/watch?v=2rKkpHLl1Ew
Re: Show HN: 8-bit Sounds – Studio2600 for the VCS (Atari 2600)
#6Can this chip only use the harmonic series as the tuning, or is it only specific to this rom's interface?
Re: Show HN: 8-bit Sounds – Studio2600 for the VCS (Atari 2600)
#7The 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.
Re: Show HN: 8-bit Sounds – Studio2600 for the VCS (Atari 2600)
#8This is extremely fun to play around with! My coworkers are looking at me funny, but it's worth it!
Re: Show HN: 8-bit Sounds – Studio2600 for the VCS (Atari 2600)
#9The 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.
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
Re: Show HN: 8-bit Sounds – Studio2600 for the VCS (Atari 2600)
#10Can this chip only use the harmonic series as the tuning, or is it only specific to this rom's interface?
All frequencies are derived from an "about 30KHz"* base frequencies, which is divided the number of times given by the value in the 5-bit frequency register. (30KHz, 15KHz, ..., 30KHz/32) This "scale" is defined by hardware in the TIA Television Interface Chip (an Atari custom chip designed by Jay Miner), which is where all the "magic" of the VCS happens.
Edit: *) There is a 31,440 Hz clock frequency used to produce NTSC signals and 31,200 Hz for PAL consoles. This is probably also what is described as "about 30 KHz" in the manual.