[time-nuts] GPS for Nixie Clock

Hal Murray hmurray at megapathdsl.net
Wed Jul 13 04:27:02 EDT 2016

> I've done NTP before, I wanted to do this with GPS since I have never  done
> a GPS implementation before.

You loose your time-nut certification unless you use the PPS.

Most low cost GPS units speak NMEA.  It's ascii text so you can debug stuff 
with your favorite terminal program.  cat works fine.

One possible quirk that may not be obvious.  The offset of the text within 
the second is not necessarily stable.  Some popular chips have 100 ms of 
wander.  By wander I mean it is stable for minutes but changes over hours.

Do you know about the GPSD project?  Lots of good info, including code.

> Xerox Alto, wow that brings back memories! My dad worked at Xerox in  Palo
> Alto for 20 years in the 70s and 80s. He primarily worked on the D  machines
> but I did get to use an Alto a few times when I was in high  school. I
> learned Mesa sitting in front of one.

> That must have been 3Mbit Ethernet right?

The Altos had 3 megabits.  Most of the D machines were on 10.  The Dorado was 

> I remember going to the lab one Saturday, they were working on a machine
> that was supposed to have a custom chip, but it was not ready, so they  used
> 7 ASICs, but those were not ready yet either, so they made a large  board
> out of TTL for each ASIC with a ribbon cable into the motherboard,  these
> boards were hung on fishing line from the ceiling so they were  just above
> the motherboard with a very short cable. That thing really  looked like
> something out of a movie. 

I don't remember that.  It was probably after I left.

The name Swenson doesn't ring any bells, but that's probably my failing 
memory.  I need some help.  What was his first name?  Got a picture handy?  
Which part of Xerox did he work for and/or what did he do?  I was there for 
late 70s and early 80s so we must have overlapped.

These are my opinions.  I hate spam.

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