27 Sep
2021
27 Sep
'21
10:05 a.m.
Most of these older fused PROMs are of comparable speed in newer EPROMs or E2PROMs. Open
collector is a hassle but not too much. One can create the needed circuits using surface
mount parts for size reduction.
A hassle but not out of the question. You usually have to go to a larger ROM size so it
can be used for additional storage with a switch or jumper select.
Dwight
________________________________
From: cctalk <cctalk-bounces at classiccmp.org> on behalf of Brian Marstella via
cctalk <cctalk at classiccmp.org>
Sent: Monday, September 27, 2021 9:16 AM
To: Jay West <jwest at classiccmp.org>; General Discussion: On-Topic and Off-Topic
Posts <cctalk at classiccmp.org>
Subject: Re: Programming Bipolar PROMs
I recently picked up an EPROM+ programming unit (
https://www.arlabs.com/eprom_plus.html) from eBay used in order to program
a couple of PROMs. Unfortunately, I haven't actually tried it yet but the
82S23 and others are supported. The owner of the company seems to be
extremely responsive to any and all questions and has a lot of
documentation on the web site.
On Mon, Sep 27, 2021 at 11:48 AM jwest--- via cctalk <cctalk at classiccmp.org>
wrote:
Jon wrote...
I can do them with the Data I/O 29B and UniPak 2B. Some of the other
UniPaks can handle them too. They are one of those devices that most of the
newer commercial programmers can't do. I wouldn't call the Data I/O really
affordable, though.
------
Same, I use a data i/o 29B for these. Jon is right, the 29B seems to have
held significant value $-wise still on ebay. But you can find a reasonable
deal once in a while.
And....
Watch out buying blanks on eBay, they're often pulls and are actually
already programmed. Also the yield was not 100% even back in the day,
apparently, so buy several to ensure you do get a good one.
------
I gave up trying to find any quantities of the 3 or 4 different bipolar
proms used for the HP 2100/21MX line on ebay. I had significant luck
contacting arcade game repair houses, and got a reasonable quantity of most
all the flavors I needed. I checked back a couple years ago and all the
usual arcade places no longer had them ?
I do believe I saw a writeup on the web somewhere where someone took a
different chip and programmed it to act like a (now) rare bipolar prom. I
don't recall how successful it was - I'd imagine the speed of the bipolars
would be an issue, plus ISTR height was an issue too (new chip was on a
carrier of sorts, creating headroom issues on some systems).
J