PC vector generator... Here's another idea...

Ok, one more quick message before I leave. :-)

Having thought over the PC-vector generator card again I have a new
"compromise" idea... I really like the ADSP2181 (Analog Devices DSP)
since it has all the vector RAM, program RAM, processor, ISA interface,
etc. essentially built in. I also like the Analog Devices dual 12-bit
serial DAC. Unfortunately they're probably not quite enough "oomph" to
do a vector generator for *all* the games that are out there...

So what I'm thinking is to use the same basic design (just an ISA card
with the ADSP-2181 on it) but then add another piece on the "far end" of
the DACs... That piece being a replica Atari Analog Vector Generator.

Use an analog MUX or two on the card and you can either have a
directly-driven voltage output DAC system *or* the AVG. Since the card
"firmware" is loaded from the ISA bus you can just load whatever you
want to use. (For applications where the direct-method is too slow, use
the AVG at the expense of some precision.)

The parts of the AVG from the DACs to the outputs are relatively cheap
(just op-amps and a couple nice caps), so that's not a big price hit for
the flexibility to do either. There's plenty of GPIO on the DSP to
control shorting the integrating caps.

I should be able to make a voltage output DAC into a current output DAC
(for the integrator) with just a resistor, no?

Comments?

-Clay

Clayton N. Cowgill Engineering Manager
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Received on Mon Apr 6 17:37:17 1998