> That's the right idea. At 500KHz there more than enough time for a 20 Mhz
> chip to drive everything. There's 100 instruction cycle time in that
interval.

Actually only 10 instructions.

> That's enough time to sample the A/D and write it to the ram. So probably
it
> wouldn't be necessary to connect the A/D directly to the RAM. It may be a
good
> idea however to supply external counters to the ram for pin efficiency. It
> would only require a 4 bit control interface and the 8 bit data interface.
> The 4 control pins are CS, WE (R/W), clear address counters, and
increment.
> Use two HCT393 ripple counters and you have a quick sequential interface
> to the RAM.

Yes, this would have been reasonable if there were 100 instructions
available, but not with only 10 instructions.


********************************************************************
Olin Lathrop, embedded systems consultant in Littleton Massachusetts
(978) 742-9014, olin@embedinc.com, http://www.embedinc.com

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