Programming Bipolar PROMs

Brent Hilpert bhilpert at
Mon Sep 27 12:52:18 CDT 2021

On 2021-Sep-27, at 8:23 AM, Tom Hunter via cctalk wrote:
> While restoring and repairing a Data General Nova 2/10 I found a bad
> bipolar PROM on the CPU board. The PROM has open-collector outputs and is
> organized as 32 words by 8 bits. It appears that one of the open-collector
> driver transistors is faulty (but it could also be that a fuse has
> "healed").
> The part is an Intersil IM5600CP, but these were also made by others, for
> example Signetics and Philips made the 82S23 and TI and NTE made the faster
> SN74S188N. Some vendors still sell these parts and there are even a few on
> Ebay.
> How do I program these PROMs? I found one somewhat obscure description of
> the algorithm in the NTE datasheet, but I suspect that each manufacturer
> had (somewhat) different algorithms.
> Is there an affordable commercial programmer out there which can program
> these PROMs?
> Is there a simple design out there which I could breadboard for a one-off
> programming job (maybe using an Arduino to control the programming
> sequence)?

The hardware & software for a one-off breadboarded programmer is, or should be, easy enough with a ~ few-hours/1-day effort if you wanted to go that route.

I did this 8 years ago for a PROM in a HP9830 - a 256*4 Intel 3601 PROM, for which I burned, and replaced with, a TI 74S387.
(In the end in turned out it was an unnecessary effort, one data-line from the PROM was showing bad but the failure wasn't the PROM output, it was the input of the IC the PROM was driving.)

Programmer hardware was 3 TTL ICs, 2 zeners, 6 transistors (more specifically 2+numDataLines) and a few resistors on a solderless breadboard, and a bench power supply for the programming voltage. Software was a python program running on a RPi. All program-pulse timing was done in user-land on the RPi.

I can send along the schematic and program if you wish, there will be some adaptation required of course. Details of the 74S188 programming/burn algorithm is in the 1975 TI Memory Databook for Design Engineers (available at bitsavers) (I expect the 188 is the most likely type you'll find NOS today).

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