Programming Bipolar PROMs

dwight dkelvey at
Mon Sep 27 12:05:29 CDT 2021

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.

From: cctalk <cctalk-bounces at> on behalf of Brian Marstella via cctalk <cctalk at>
Sent: Monday, September 27, 2021 9:16 AM
To: Jay West <jwest at>; General Discussion: On-Topic and Off-Topic Posts <cctalk at>
Subject: Re: Programming Bipolar PROMs

I recently picked up an EPROM+ programming unit ( 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>

> 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

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