ID UV erasable PROMS used on an IBM PC board?

Chris Elmquist chrise at
Wed Mar 23 12:28:34 CDT 2022

On Wednesday (03/23/2022 at 04:18PM +0100), Christian Corti via cctalk wrote:
> On Wed, 23 Mar 2022, Chris Elmquist wrote:
> > More interesting.  If the programming algorithms remained the same then I
> > guess it is just an issue for the programming system--  when it auto-IDs,
> > it should display (and allow!) 27C256A instead of 27C256.
> > 
> > I guess the next question is whether the programming algorithms really
> > are the same between the 8CH and the 8DH variants??
> > 
> > My limited testing suggests they are at least compatible since my 8DH
> > appears to be working when programmed as an 8CH.
> I didn't even know that primitive EPROMs have device IDs...
> Without looking for a data book, how is the ID mechanism implemented?

Intel called it "Intelligent Identifier(tm) Mode".

 From page 5-43 of my 1991 Intel Memory Products book, for the 27256,

You put Vh (+12V) on address A9 and then,

with A0=0, you will read out the manufacturer ID
with A0=1, you will read out the device ID

Chris Elmquist

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