Need Help Programming DIP 64 IC

Thread Starter


Joined Jul 6, 2020
Hi, I have zero knowledge of IC and these electric components. I have a machine which has safety module card on it. The machine is giving was start test error. On getting it checked locally by a technician they have figured out one IC on the board is not working properly. Our machine uses two such safety module cards and those cards are interchangeable. One of the safety module card has the working IC on it. I want to copy program from that working IC to this new replacement IC I have bought from HKInventory website.

The IC model number is M50747ESP

I am from India and I am not able to locate a person who can do this work for me.

It would be of immense help if you could guide in some direction to solve this.


Joined Mar 10, 2019
Reading the datasheet, there does not seem any way to program that chip externally. It was produced with a MASK ROM file that the buyer sends to the manufacturer. It is a ROM, not a PROM, suggesting a new chip is not programmable in the field.
It may be possible to read the ROM via some external programmer or interface. The ROM address starts at E000H. You could build some simple address generating interface and read the data lines to read the ROM
Now, the "E" in the ESP designation may be different design. Hard to find a datasheet for the "ESP" specific version, they seem to be "XXXSP". It may mean an EPROM, but maybe not.
Maybe someone else here on the forum has programmed these and can tell you how.


Joined Jan 30, 2016
Yes, I came to same conclusion. All the datasheets I could find initially suggest its a factory mask programmed device


A lot of vendors offer parts that are clearly pre-programmed. This chip circa 1989/early 1990s was apparently common in typewriters, copiers, etc. so I guess there's stacks of inventory of useless parts (unless you know the specific mask code).

There have been several posts on Stack Exchange (same link as above) and elsewhere that came to the same conclusion - you can't get the data out. However, it seems that only applies to the mask programmed M50747-xxxSP and one-time programmable M50747E-xxxSP devices, bit not the M50747ES UV erasable version which has been alluded to, but not seen.

A bit of Google spelunking found this 1989 Mitsubishi publication from which I've extracted the attached M50747ES data sheet and the extract below... So, as long as the OP's device has a window covered by a label and is socketed then it's doable. Finding a programmer might be tricky, but it shouldn't be hard for someone to knock up something on an Arduino. I could offer a schematic and some code to do so as a starter... let me know.