🚀 go-pugleaf

I want to send data out to 4 12 bit D/ACs as fast as possible. (There is 
more than that in this story, but for now, that is enough.)

At the moment, I am sending data byte by byte using I/O instructions 
to a PC bus D/AC card. I have to perform 9 byte output instructions to get the 
data from memory onto the card's analogue output lines. A transfer cycle 
takes about 18 usec to complete. This is about 55kHz or 55kx9 = 495kbytes/sec.

My machine is a 33Mhz 386 AT bus box, without too much that looks special to
my (untrained) eye. I have no idea at all about wait states etc.

I am looking at building a new D/AC card using the AT bus that will be driven 
by my the 386's DMA controller chip. I am looking for data transfer rates in
the order of 1Mbyte/sec or better. the CPU will be doing nothing special
and so I am happy for its performance to be reduced by up to 90%. The
key factor is getting the data out as fast as possible on this machine.

Could someone give me an idea of the data transfer rates I might expect from 
such a setup?  Failing that, what is a good reference on this topic that 
might tell me?

Sam Lander

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Sam Lander, Department of Psychology, University of New South Wales, Australia.
86b0062@csdvax.csd.unsw.edu.au or 90b1182@csd3090.csd. ... Phone 61 2 697 3030.