17 May
2011
17 May
'11
12:41 p.m.
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
Such equivalents lists were published in HP Bench Briefs, which are on
the web somewhere. Be warned that later lists do not necessarily incldue
devices that were on earlier lists (it appears that a device was only
included if it was used in an instrument still supported by HP), so you
may need to check several lists to find the device
Functional work alike but needs thought on fitting
eg changing series from 74 to 74F to get something working.
But watch out for devices which are not the same in differnet families.
The common examples are TTL And-Or-Invert gates which have more inputs in
some familes than in others. The 74H71 and 74L71, though have almost
nothing in common (well, they're both flip-flops...)
And cases where a component was a failure and dropped
in favor of an
improved b version
sometimes including circuit modifications
And the times that ICs have been redesigned but kept the same number.
IIRC the LM379 dual audio amplifier went thoguh a redesign which even
changed the number of pins on the package. This IC is used as a servo
ampliifer in some hard drives (Micropolis 1200s) and as a deflection
ampliifier in some vestor displays (Vectrex at least), so you might come
across it in a classic computer.
-tony