18 Dec
2005
18 Dec
'05
4:10 p.m.
On 12/18/2005 at 11:03 PM ard at p850ug1.demon.co.uk wrote:
Juat watch out for some 74Hxx numbers (used in
1970's HP calculators,
maybe minicomputers). Those can have pinouts very different from the 74xx
device of the same number. There are even a few 74xx and 74LSxx parts
with different pinouts (the 7451 being the most obvious example).
...and then there are parts like the 74L85/74C85 with wildly different
pinouts from the 85, LS85, ALS85, HCT85, etc...
Another thing to be aware of is that while pinouts may be the same for
parts, functionality may be quite different. Case in point: the
pedestrial 74107 JK FF; the 74107 is level-triggered; the LS107is
edge-triggered. It can make a big difference in some applications.
Cheers,
Chuck