These days you can pick up a CPLD for $1 so I just have a tube of those
and can replace pretty much any jelly bean TTL logic. Less parts to
have to keep around or order.
If you are just starting out, there's nothing like learning with actual gates
that you can touch. Once you are beyond that though, I would argue
than 74XX of any family is essentially dead except for very simple or specialized
cases, to be replaced by some mix of micros, CPLDs and FPGAs. I occasionally
use the single gate chips as well as the voltage translating bidirectional buffers
to go between say 5v and 3.3v logic, but that's about it.
Now if you are just in love with 74XX series stuff, check out these chips,
74XX at 1Ghz speeds!:
http://www.potatosemi.com/But I agree that the choice comes down to what's the best fit for the application.
I was looking at the most recent issue of Nuts & Volts and there's a page
about building a countdown timer for a basketball game. The circuit
is a 555 driving a string of counters followed by 7 segment decoders. But nooooo, this
is how to build it in 1972, not 2010! This application calls for a 40pin micro
and some driver transistors. Many fewer chips, more reliable. The count
frequency is clearly within the capability of any micro. Now if you're going
off on some retro design thingy, that's another story. And yes, I suppose you
could argue that N&V's audience is the absolute beginner and how else do you
learn without going down to the gate level?
When's the last time you saw new circuits using those hot new RTL and DTL chips?
Heck, how many people even see ECL designs these days?
And there are some applications where discrete gates just aren't going to cut it.
Trying doing a state machine with 74XX? Good luck! Even back in the day,
many state machines were done with counters driving bipolar PROMs. Actually
I have seen a state machine with TTL logic, an 18" X 18" board stuffed with chips!
Anyway, my 3 cents.
Scott