Difference 23512 and 27512 Eprom

From: Dwight K. Elvey <dwight.elvey_at_amd.com>
Date: Thu Oct 21 16:01:44 2004

>From: birs23_at_zeelandnet.nl
>
>Hi,
>
>I know very little about electronics and eproms so this question might be
>really easy. I would like to know what the difference is between a 23512
>eprom and a 27512 and if there are any differences if its possible to make
>some sort of adapter. Had a look at some schematics and they looked the
>same to me, data lines on the same pins etc.
>
>Any help is welcome.
>
>Ow the reason I want to know this is that I want to read some old roms in
>my EPROM reader.
>
>Cheers,
>
>Stefan.
>
>

Hi
 I think that the 23512 is a EEPROM and the 27512 would be a normal
EPROM. The biggest issue is what to do with the programming voltage
and any auto type sensing. Most newer programmers have a way to
set the programming voltage to 5V instead of what ever. They also
usually include some way to turn off the auto sense that would otherwise
bring one of the pins to a higher than normal voltage. If those
two conditions are met, you should be able to read the 23512.
 If there are issues with the select lines being inverted between
the two, I often stack two machine pin sockets. I then can cross
wire what I want by either popping out an unwanted pin or breaking
off the tip of one that I don't want to have connected.
 For these two parts, I believe that the address and data line
match.
 Note that many programmers keep the programming voltage high,
even when reading since the newer EPROMs are strobed with a
TTL level input for programming. So look out for this. Even if
you don't tell it to program, it can have an unexpected high
voltage on one of the pins.
Dwight

Dwight
Received on Thu Oct 21 2004 - 16:01:44 BST