[sdiy] Another new hard to find part....

[Roy J. Tellason]

On Tuesday 06 July 2004 10:27 am, Ingo Debus wrote:

> Logic ICs have been obsoleted all the time. Well perhaps not really
> obsoleted, but they didn't make the transition to newer logic families
> (from standard TTL to LS or HC).

I actually have a bunch of the original "standard" TTL chips kicking around. 
I'll use those when what I'm doing only involves some small number of them, 
and the power requirements aren't going to matter that much.  I also have a 
bunch of 74H stuff from a scrapped mini (A Burroughs B500 as I recall) but 
most of them are marked with proprietary numbers and aren't going to do me 
much good unless I find a cross-reference somewhere.

What I don't understand is the point of numbers like 74HC4xxx,  where they're 
(apparently?) giving you the function of a 4000 series part but putting a 74 
in front of it?  Maybe I'm just missing the point as I have not yet seen a 
databook for these newer families.

And I remember reading somewhere that the whole 4000 series was going away. Is 
this the case?  If,  as I have the impression of but am not sure,  the 74HC 
and similar parts will only work with lots lower voltage supplies,  that sure 
is going to limit some options.  I kind of liked the idea of a logic family 
which would run on 15V or so,  and sometimes even wished that it were higher! 
(Like being able to run something off a split supply like what's typical for 
op amps.)

I got a hold of my first (TI) TTL book in 1970.  Got a few since then,  a  
Motorola one,  I think,  that has the LS stuff in it,  and I think that 
there's one that includes the "F" series and similar.  If somebody has a 
later one that covers some of these other families,  or know some place where 
I can find a good discussion on what the differences are between the 
families,  I'd sure like to hear about it.  Or if you have recent books you 
don't want,  contact me off-list and we'll work something out...