On May 17, 16:43, John Honniball wrote:
> I've checked my "System 74 Designer's Manual", and it's
I no longer have my really old Texas TTL data books -- the oldest I have is
1982 -- but didn't one of th eold ones have a short chapter describing the
evolution of TTL, S and H series, and LS? I thought it might have dates.
> But an oddity did show up: the chip pinouts sometimes
> differ between ordinary 74 TTL and the 74H version. A 7401
> has a completely different pinout from a 74H01, for
> instance. And a 7454 has one less input than a 74H54 (it's
> an AND-OR-INVERT chip). I hadn't spotted that before.
Yes, a common pitfall. I got bitten by that :-) And the 74150 has the
same number and arrangement of pins as the 74ALS150, but one is 0.6" wide
and the other is 0.3" wide!
--
Pete Peter Turnbull
Network Manager
University of York
Received on Thu May 17 2001 - 14:00:20 BST