ID UV erasable PROMS used on an IBM PC board?

Chris Elmquist chrise at
Tue Mar 22 13:56:03 CDT 2022

On Monday (03/21/2022 at 09:17PM -0700), Glen Slick via cctalk wrote:
> On Mon, Mar 21, 2022 at 8:25 PM Chuck Guzis via cctalk
> <cctalk at> wrote:
> >
> > The PROMs are most likely house-labeled Intel commodity parts with
> > JEDEC-standard pinouts, so it should be fairly easy, using an EPROM
> > reader, to figure out if these are 8KB, 16KB, 32KB or 64KB devices.
> Some device programmers can read the manufacturer and device ID codes
> from a device, if they are implemented. That would be another way to
> check for a Intel standard part.


> Intel 27256 - 89h / 04h
> Intel 27C256 - 89h / 8Ch


Trying not to hijack the thread too much but I have an Intel D27C256-200
here in my TL866II+ programmer and it returns ID  89h / 8Dh.

The TL866+software actually fails to program it if the "Check Id"
feature is enabled as it complains about ID mismatch.  But if I disable
that, it programs correctly and works in-circuit without issue.

Without disabling the Id check, there would be no way to program an
Intel 27256 on this programmer since there are no other 256K-bit Intel
offerings in the menu-- so I am suspecious of the situation.

Any idea why some Intel 256K-bit PROMs are 89/8C and some are 89/8D??
Chris Elmquist

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