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[Discuss-gnuradio] ADC tied directly to CPU?

From: Bryan E. Chafy
Subject: [Discuss-gnuradio] ADC tied directly to CPU?
Date: Fri, 21 Jan 2005 17:39:27 -0500 (EST)

How feasable would it be to directly interface an AD to a pentium (1,2,or 3)
class CPU?
For raw AD sampling say a satellite IF signal, the USB and even PCI is marginal
at best.  Also, the protcols are not simple (nothing is easy and synchronous,
always a burst, always a delay).  PCI/USB make FPGA's almost a requirement.
PCI Express looks nice and fast, but it's far away from cheap or practical at
this time.

I was thinking something like Fig 9-11, or 9-12 in the following page:
It appears to look straightforward enough, but would the same concept
work with a modern cpu/mobo combination?

I dont mean to create a new circuit board, but simply homebrew
solder an AD converter directly to the CPU pins underneath an ordirary
motherboard.  Doing an "in" at some hardwired address would read the contents.
Since the FSB of a P3 class is 100 or 133mhz, a highspeed AD could be used
(or slower if the clock is divided down).
If successful, I know starvation is a problem at these rates, but if more
than one motherboard were wired up in this way, perhaps some
parallelism/staggering could solve that.?

Just a thought on highspeed AD on the cheap.

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