ID UV erasable PROMS used on an IBM PC board?

Glen Slick glen.slick at
Wed Mar 23 12:56:52 CDT 2022

On Wed, Mar 23, 2022 at 10:38 AM Chris Elmquist via cctalk
<cctalk at> wrote:
> On Wednesday (03/23/2022 at 04:18PM +0100), Christian Corti via cctalk wrote:
> >
> > 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

It is interesting that the Table 1 Operating Modes referenced above on
page 5-43 says that the Manufacturer ID is 89H for UV erasable Cerdip
parts, and 88H for OTP Plastic parts.

The interesting thing is that previously Intel data books (e.g.
1983_Memory_Component_Handbook.pdf, page 4-28) said "All identifiers
for manufacturer and device codes will possess odd parity, with the
MSB (D7) defined as the parity bit". The Manufacturer ID of 88H does
not have odd parity. I don't know if the odd parity requirement was
removed, or if this is an exception.

More information about the cctech mailing list