[time-nuts] GPS for Nixie Clock

John Swenson johnswenson1 at comcast.net
Tue Jul 12 21:15:31 EDT 2016

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

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?

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.

John S.

On 7/12/2016 1:21 PM, Hal Murray wrote:
> time at patoka.org said:
>> In addition, even MCU has not enough resources to handle TCP/IP, DHCP  and
>> NTP, it is some solutions available to outsource it to dedicated  chips. I
>> was using WIZ5100 (assembled as a modules) with great success.
> NTP is pretty simple.  If you are willing to take a few shortcuts, things get even simpler.  If you have a NTP server on your LAN, you can skip routing and DHCP by broadcasting a request.  It would be interesting to see how small you could make a set-the-time package.
> The Xerox Alto had an Ethernet boot loader in microcode.  (and space in the microcode ROM was tight)  When bringing up a new machine, we figured out that it was much simpler and faster to debug the Ethernet before the disk controller.  The debugger worked over the Ethernet.  That gave you a solid place to stand early in the debugging process.

More information about the time-nuts mailing list