#tms2532

OPROM: Obscure Programmable Read Only Memory

I kept trying to dump the control ROM from my H19.  It’s a simple 512-byte ROM to bring the terminal to a functional state.  Every time I dumped the contents of the ROM, I would only get the first 256 bytes of data.  Depending on settings, I either got garbage after that (or vice-versa), or a duplicate of the first 256 bytes twice in a row.  No dice...

Hotwiring A11 to +5V didn’t change anything either.  My guess was that A11 on an EA8332 isn’t on the same spot as the veritable 2732 equivalent.  Time to dig up the datasheet!

Seems that trying to find information on the NEC/EA8332 PROM will get you... nowhere.  Acknowledgement of this PROM is pretty sparse out there on the web.  By chance, I found a scan of a 1980 AMD Advanced Micro Devices parts catalog listing all the chip equivalences between other manufactures and their devices. Looking up the AM9232 (the equivalent PROM) again lead nowhere.

I spotted a few different versions of the same PROM between manufacturers, including Texas Instruments.  Those guys usually have good documentation, right?  Seems that finding information on a TMS2532 is significantly easier.  Lo and behold, A11 sits on pin 18 rather than pin 21 like I expected.  After a fresh jumper modification, I was able to dump the second half of the PROM. 

Now I just need to figure out how to add a custom pinout profile to the Willem EPROM burner software so I don’t have to do something so ridiculous in the future.