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).
