Fwd: [roys-tech-chat] Building replacement for TTL counter DM8552(National Semiconductor)

[Brent Hilpert]

"Roy J. Tellason" wrote:
> 
> Have any of you guys ever heard of this chip?  It's new to me...
> 
> ----------  Forwarded Message  ----------
> 
> Subject: [roys-tech-chat] Building replacement for TTL counter DM8552
> (National Semiconductor)
> Date: Thursday 10 April 2008 08:58
> From: "Michel" <itloiiw at yahoo.com>
> To: roys-tech-chat at yahoogroups.com
> 
> Hello all,
> 
> I am trying to repair a Systron Donner Frequency Counter model 6254
> that does not count well. This counter is build with "simple" TTL
> chips only. (I have no manual nor schematic).
> The culprit (found by swapping chips) is a TTL chip from NS : DM8552
> It is a decade counter with latches and tri-state outputs.
> Since I did not find any source for replacement chip, I have thought
> to build some equivalent circuit with maybe 74LS160 and 74LS393.
> My problem is that I have no datasheet except pinout for DM8552
> (found there http://www.datasheetarchive.com/pdf/1215336.pdf ).
> Does anybody have more information about it ?
> 
> Many thanks in advance,
> Michel
> Grenoble - France.

Usually I'm asking about weird NatSemi chips, but this is one I can help with,
I have it documented in a 1976 NS TTL databook. I'll communicate with the OP to
try to get info to him. The 8552 has some other unusual features to support zero-blanking.

(..always happy to talk about electronic counters, just yesterday I got an HP
524B from
1957 functioning, after two weeks of cleaning it up.
It's a boat anchor, but it's tube digital (84 tubes). (But it's probably OT for
this list).