Unknown TI logic series

[Brent Hilpert]

On 2010 Dec 19, at 10:28 AM, William Donzelli wrote:

> And as for DEC - remember that they sometimes used ICs in somewhat
> unorthodox ways that may not be tested for back at the vendor. It seem
> to recall that one of their favorite tricks was to use some of the
> internal "diodeness" of the input and output pins of line transmitters
> and receivers for clamping.

I'm reminded of the PDP-8/m front panel problem discussed on the list a 
few years ago, where the design was relying on non-specified behaviour 
of an IC type and turned out to be very dependant on both the 
manufacturer and time frame of IC production.
(Collector triggerring of a 74175 FF: 
http://classiccmp.org/pipermail/cctalk/2006-September/224592.html)