A Race to Bottom… of Sound Chip Specs [Updated]

Update 3/18/2013 (6:21 PM):



Well, it didn’t take long for things to go back to normal.  Maybe I should’ve held off posting this just for a little while longer.  Oh well.

As a bonus, here’s the coloured image of Pohena I meant to show earlier:

“I’m not a prize, you idiot.”

W-well, I didn’t mean it like that.   Uh… awk-ward.



Well, it seems that in my attempt to reorganize the files on my “website”, I did something that caused all the images on this blog to break (Dammit, I’m a computer scientist, not a web administrator!).  I’m in the process of getting that fixed.

In the meantime, let talk about something that doesn’t involve anything hosted on my site.

In my introductory post of Gonna Catcha, I posted this music sample from the project:

It was my attempt at emulating the style of music from 80s arcade games, without actually knowing how it was actually done.  Being someone who spent 3 years working on a master’s thesis on computer-generated sound,  this just simply wouldn’t do.  Nope, nope, nope.avi.

As with the graphics, I turned to Pac-Man  for inspiration:

The game used a chip called the Namco WSG to generate sound.  It had 3 channels, each could play one of the 8 waveforms stored in 256 bytes of external memory (PROM).  These waveforms could be customized to the sound guy’s heart’s content, which resulted in the highly-memorable audio of games such as Pac-Man.

This also stands in contrast to early PCs and early home consoles that came around the same time as or after it.  Although some of them did allow custom waveforms either intentionally or via programming exploits, they mainly relied on programmable sound generators (PSG) that only played preset waveforms to generate sound.  Some examples are (off the top of my head):

  • AY-3-9810 – found on earlier models of MSX computers
  • MOS Technology 6581/8580 (SID) – found on the Commodore 64
  • Ricoh 2A03/2A07 – found the NES
For comparison, listen to the NES port of Pac-Man:
Even though the sound generation of these chips weren’t as sophisticated (well, the SID was sophisticated in other ways), it didn’t stop them from being popular even to this day, even more than these old arcade chips.
Enough digression, time for the main event.  After applying the knowledge above, I have created the following early-80s-style arcade-type music:

Track list:  Donum Start ~ Donum Level ~ Donum Defeat ~ Pohena Start ~ Pohena Level ~ Pohena Defeat

I couldn’t find a way to generate 4-bit samples; everything I had to work with had a minimum bit resolution of 8 bits and the bitcrushers (a digital audio effect that reduces the number of bits used in an audio signal) I tried didn’t produce the desired results.  So essentially, I doubled the amount of pretend PROM on my pretend arcade board and used 8-bit samples.  Otherwise, I’m satisfied with the result, at least for now.  Personally, I find both “Defeat” tracks to be quite funny.

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