21MX proms (per request)

Alexandre Souza alexandre.tabajara at gmail.com
Mon Sep 7 10:34:20 CDT 2015

As I said in the original post I wrote, sometimes you gotta use flash
devices that are WAY faster than common EPROMs...

2015-09-07 12:32 GMT-03:00 John Robertson <jrr at flippers.com>:

> On 09/06/2015 2:00 PM, Alexandre Souza wrote:
>> Jay, no one is pin compatible, I always make adapters. But at least I make
>> it work :D
>> 2015-09-06 16:00 GMT-03:00 Jay West <jwest at classiccmp.org>:
>> Alexander wrote...
>>> -----
>>> Intersting to note: many times i have used eproms in place of these
>>> proms.
>>> Usually, flash parts are faster, so better suited to the task.
>>> -----
>>> Loader roms:
>>> You may be able to get by with that on loader roms. I've never found
>>> eproms that were functional & pin compatible. What ones did you use for
>>> the
>>> 1K variety?
>>> Microcode:
>>> I doubt seriously the eproms would be stable for microcode. HP specs 5ns
>>> speed parts for the microcode; what eproms work and can hit those
>>> speeds? I
>>> suspect this is one of those "might seem to work" but is a really bad
>>> idea.
>>> J
>>> As Jay points out, it is the access speed required by the device you are
> substituting the EPROM for a ROM/PROM that counts. In some cases the 100 to
> 400ns access speed of EPROMs won't matter (clock of under 1mHz for 400ns
> 2716s to around 4mHz for 100ns EPROMs), but if you are running 10mHz or
> faster reads then I suspect you will have problems unless you find faster
> devices than EPROMs for your substitute ROM/PROM...
> John :-#)#
> --
> John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
> Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, VideoGames)
>                  www.flippers.com
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