On Mon, 30 Jan 2012, Steve Nickolas wrote:
Get the synthesizer IC used in the IIGS, that's so much fancier than the 8910.On Mon, 30 Jan 2012, Sean Fahey wrote:On Monday, January 30, 2012 1:45:30 PM UTC-6, Steve Nickolas wrote:Fortunately, a simple beep's all I need.Beep.LOL.Actually, I'd been thinking of how I could design a "neovintage" computer, and put concepts of various computers into a blender. I figured for a CPU I'd use a 65C02, for video 6847, for audio AY-8910. As far as sound goes that meant the hardware would basically be a Mockingboard mapped to a different address. >:P
That sound generator was designed for games. It has limitations, not in terms of the frequencies it can generate (since frequency is controlled by a string of programmable dividers, one can get just about any frequency) but the waveform is limited, as is some of the control functions. But it certainly offloaded a lot of stuff at a time when the CPUs were quite limited.
Right about the same time, there were plenty of articles about using the 6502 (and other CPUs) for generating sounds or even music, but they tended to be about standalone work. So you could do music synthesis with a 6502, but it would get in the way if all you wanted was a Beep while you did other things with the 6502. Hal Chamerlin's book about using microprocessors for electronic music details it well.
This late in the game, one might as well add a second 6502, and whatever hardware like a DAC is needed. Much of the RAM can be used for the sounds/music (and that RAM is so much easier when you can put the full 64K in a single IC), and then figure out how to control it from the main 6502. So instead of generating tones, and then waveshaping, you can generate a more exotic waveform at the desired frequency, and so on.
I seem to recall there was some add on for the Apple II that went this way, rather than adding something like the 8910.
Michael
I prolly won't be able to design a physical version but I've been trying to design it practically, as in, would this work if the machine were really built with the tech of the time?Conceptually, though, I could in fact implement it in *software* - just like one would implement an emulator. And if I needed to learn anything in the process, I could rewrite Dapple with the new knowledge too.Implementing a system beep via the Mockingboard sounds impractical, but against the masterplan it was what I wanted to do.(BTW, a Fine tone of "69" is closest, afaict, to the system bell. I think 80 sounds better though. And if I could somehow make a "dink" instead of a simple beep that would be nice too.)-uso.