I vaguely remember that all 2532 and 2732 EPROMs were compatible *except* the TI one. (or was it an other manufacturer?) Memory is dropping bits :-( Check the board before you install a 2732 ! It's of course OK to put in an other TI 2532 (same as the original one). - Henk, PA8PDP. ________________________________ Van: cctalk-bounces at classiccmp.org namens Bruce Lane Verzonden: za 03-12-2005 06:17 Aan: cctech at classiccmp.org Onderwerp: EPROM Substitution Fellow techies, I've got a nice item of Z80-based, 1986-vintage, telephone test gear that I'm trying to restore to working condition. The CPU board, as it currently stands, uses a pair of TI 2532 EPROM chips for program memory. I suspect both chips have become borderline in terms of their timing tolerances, so I need to replace these with the more readily available 2732, of which I have plenty. The pinout between the two chips is slightly different, thanks to the fact that the 2532 has only one enable line and the 2732 has two. I've come up with an idea for conversion, but I'd really like to get a sanity check on it, preferably from someone with an original TI data book that covers the 2532. Here's what I've got so far, based on comparing the pinouts of the two devices. (1) Move the trace originally connected to pin 18 (A11) on the 2532 up to pin 21, which appears to be A11 on the 2732. (2) Tie pin 18 to pin 20 so that, on the replacement 2732, both /CE and /OE are asserted simultaneously. Did I miss anything? Thanks much. -=-=-=-=-=-=-=-=-=-=-=- Bruce Lane, Owner & Head Hardware Heavy, Blue Feather Technologies -- http://www.bluefeathertech.com kyrrin (at) bluefeathertech do/t c=o=m "If Salvador Dali had owned a computer, would it have been equipped with surreal ports?" This message and attachment(s) are intended solely for the use of the addressee and may contain information that is privileged, confidential or otherwise exempt from disclosure under applicable law. If you are not the intended recipient or agent thereof responsible for delivering this message to the intended recipient, you are hereby notified that any dissemination, distribution, or copying of this communication is strictly prohibited. If you have received this communication in error, please notify the sender immediately by telephone and with a "reply" message. Thank you for your cooperation.