mk79 wrote:Does anybody know how the clock for the AY chip is derived? I don't understand this from the posted PCB photos.
I seem to be seeing it's simply using /VMA or E (presumably the latter) - which should roughly be 2MHz signals.
mk79 wrote:Does anybody know how the clock for the AY chip is derived? I don't understand this from the posted PCB photos.
Interesting. The QSound code suggests it expects the input frequency to be 1.5MHz. The E signal however only carries a 750kHz signal (just measured and according to the 68008 manual it's CLKCPU/10, so that checks out). That's exactly halve, surely not a coincidence, but I still don't quite understand it.tofro wrote:I seem to be seeing it's simply using /VMA or E (presumably the latter) - which should roughly be 2MHz signals.mk79 wrote:Does anybody know how the clock for the AY chip is derived? I don't understand this from the posted PCB photos.
Don't bother, I have the source code. However, it was barely more readable than a disassembly before I started working on itDerek_Stewart wrote:Looks like another disassembly job...
For the yet unreleased Q68 AY implementation, I decided for the Atari ST frequency of 2 MHz. Reasons:mk79 wrote:But the important thing is that the QSound has apparently a chip frequency of 1.5MHz. The Spectrum has a frequency of 1.7734MHz and the Atari ST uses 2MHz. So the question is, which frequency makes the most sense? There are not many QSound boards or software for it around (is there any software besides the demos supplied with it?), so compatibility isn't that much of a concern really. My personal feeling, if one was to resurrect AY sound for the QL, would be to go with the Spectrum frequency. There are tons of existing sound files for this frequency. Any other thoughts?