On Wed, Mar 23, 2022 at 10:38 AM Chris Elmquist via cctalk <cctalk@classiccmp.org> 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.
