Important Xref data question.

To me there are a number of aspects. Equipment makers part number to actual part number eg HP 1820-xxxx 74lsxxx there are some lists you can start to populate your database Component manufacturers second sourcing eg a Texas SN74xx to National DM74xx A work alike and can be used to replace some specs may be better NEC V20 (?PD70108) was a processor made by NEC that was a reverse-engineered, pin-compatible version of the Intel 8088 and see http://en.wikipedia.org/wiki/NEC_V20 Functional work alike but needs thought on fitting eg changing series from 74 to 74F to get something working. And cases where a component was a failure and dropped in favor of an improved b version sometimes including circuit modifications The possibilities are almost endless, the amount of data entry is huge, I did start with an HP parts table some years ago myself but other stuff got done instead. Dave Caroline On Tue, May 17, 2011 at 1:49 AM, Geoffrey Reed <geoffr at zipcon.net> wrote: