Is there a datasheet available for ST M27C128B?

[EIcs.1]

I recently purchased some secondhand ST M27C128B-12F1 online and am trying to program them correctly. The main information I am looking for is the Device ID, Vcc for writing and verifying (both), and Vpp. I was able to find a datasheet for the M27C128A but am not confident these parameters are the same.

Thank you!

[Peter BENSCH]

Welcome, @EIcs.1​, to the community!

The M27C128A was discontinued many, many years ago and there was never an M27C128B, you probably have a counterfeit device.

We can easily see more if you post a picture of it that is as detailed as possible?

Regards

/Peter

[EIcs.1]

Thank you Peter. I uploaded a couple images to imgur of the EPROMs, I also bought some "M27C256B" which are pictured.

https://imgur.com/a/uZTS7Jx

[Tesla DeLorean]

There seem to be contemporary profiles for these types of devices from SGS-THOMPSON / STMicroelectronics

Could be a die shrink, or second source agreement with about a dozen people making equivalent devices.

In any case you're so far beyond the sell-by date, it's probably unrealistic to get any type of support beyond that you can test/evaluate for yourself.

What's the Electronic ID report? You should be able to read it out via the programmer.

These should be 12.75V +/-0.25V programmed devices

[EIcs.1]

It looks like the electronic ID is 20 89. Here's a screenshot of the profile I made in my programmer software.

 

I chose 13.00V for programming, 6.50V for Vdd Write, and 5.0V for Verify which was close to the specifications from the "A" device, see screenshot from datasheet. Does that seem right?

[Tesla DeLorean]

That's the code for the NMOS M27128A, the CMOS M27C128A was 0x20,0x0A

That wants 6.00V