17 May
2001
17 May
'01
7 a.m.
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