[sdiy] pre Uprocessor schematics with ADC/DAC?

Aaron Lanterman lanterma at ece.gatech.edu
Thu May 28 00:58:58 CEST 2009

On May 22, 2009, at 12:48 PM, Scott Nordlund wrote:

> I have looked at the Synergy schematic, but it was only briefly and  
> I didn't have a chance to make much sense of it.  Would you say that  
> it performs more or less as a "coprocessor" that is largely  
> controlled by the CPU (for the state machine, etc.), or does it act  
> as a more or less autonomous unit, like the OPS/EGS chips in the  
> DX7?  I got the impression that it was more of a "coprocessor", in  
> which case I wouldn't be able to make much sense of it without  
> understanding how the CPU interacted with it.

Probably the coprocessor analogy is the best one. The main  
housekeeping in the Synergy is done by a Z-80, which sets various  
registers on the digital oscillator board, which then kind of runs off  
and does its own thing.

There are a couple of journal paper by Hal Alles that spell out the  
architecture in quite a lot of detail. This is what you want:

H.G. Alles, "An Inexpensive Digital Sound Synthesizer," Computer Music  
Journal, Vol. 3, No. 3, Fall 1979.

H.G. Alles, "Music Synthesis Using Real Time Digital Techniques,"  
Proceedings of the IEEE, Vol. 68, No. 4, April 1980, pp. 436-449.

- Aaron

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