74123... What's it do?

From: Richard Erlacher <edick_at_idcomm.com>
Date: Sat Jul 10 21:09:37 1999

A 74123 is a retriggerable one-shot. For a given trigger transition, it
outputs a pulse of very approximately calculable duration and, should it get
another such trigger before it's done with its current pulse, will continue
that pulse until the predtermined pulse duration after the last such
trigger.

If you work for many companies and use one in a circuit, you will be fired
without further ado. That was SOP at Martin Marietta when I was there. I
even saw a manager back a guy into a corner to get him to save everyone the
embarassment and just quit.

There is no justification for using such a device with today's circuitry,
and the passives which make it stabile and predictable for practical use all
cost more than an equivalent precisely timed circuit.

Now watch the guys jump on this one because they got one to work once upon a
time. . .

Dick
-----Original Message-----
From: Bill Sudbrink <bill_at_chipware.com>
To: Discussion re-collecting of classic computers
<classiccmp_at_u.washington.edu>
Date: Saturday, July 10, 1999 2:49 PM
Subject: 74123... What's it do?


>I know that it is a "one-shot". What does that
>mean? The pinouts in the Chip Directory are
>no help. Several seem to be involved in the
>DEPOSIT logic on the IMSAI front panel.
>Also, I can't quite figure out what the logic
>table for the 74107 is trying to say.
>
>Thanks,
>Bill
Received on Sat Jul 10 1999 - 21:09:37 BST