21MX proms (per request)

Jon Elson elson at pico-systems.com
Mon Sep 7 17:05:29 CDT 2015

On 09/07/2015 12:47 PM, Sean Caron wrote:
> But I do think there's merit in Alexandre's general argument that one could
> theoretically emulate the older bipolar PROMs with some mix of modern
> components ... and the programmable device would be (a) more easily
> obtainable than the old bipolar PROMs and (b) programmable with
> inexpensive, contemporary USB device programmers which are definitely big
> positives.
Most likely, one could use a parallel modern EPROM that is 
as fast as the old bipolar PROM.
Of course, the pinout would be totally different, probably 
in a larger size package with way more pins.

This one is 256K and 70 ns access time.

If you REALLY need it fast, Winbond has a 45 ns EPROM, but 
not in stock at Digi-Key.
That's their W27C512-45Z


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