[qrmn]

I do remember disassembling it and looking at it from the other way! (I was curious.) Pre-emptive multi-tasking kernels at that level weren't things you saw frequently on consoles then. Many people just hung things off the vertical blank instead.

You can decode the audio bits - it's just Sony's special version of ADPCM - or use a cartridge (for those PlayStations old enough to have a cartridge port) and read out the SPU memory over X-Link. You didn't even need a debug model to do it (although you did need a handy parallel port and the ability to bit-bang, or run a DOS program).

The CODEC used CD-XA Mode 2 Form 2 (2532-byte sector, with less error-correction layers) ADPCM-compressed streaming audio, 1 of 8 channels, at a relatively low sample rate - which works fine for speech. Lots of PlayStation games used the same basic technique for music and voices (as well as FMVs, although the bulk of that data would have been MDEC-compressed video).

[malkia]

I've got more familiar later with PS2, as I move to another studio, and was an audio programmer there (Treyarch) and had to do a lot of "PS1" programming on the SPU. I was later reading an article on the TRON operating systems, and found that a lot of the primitives on the PS2 were based on it, even the scheduler to the point - https://en.wikipedia.org/wiki/TRON_project - but never got much of it.

Oh, these were some exciting times! - the whole systems was there open for you to see (at least from the software level, and to some point HW).