So I wrote a Python script to simulate a modem successfully connecting to a time server that sends ACTS¹ time data.

And it works! (not sure why the video doesn’t embed)

http://drop.duvert.net/atomicclock/atomicclock.mp4

I quite like the DATE/TIME SYNCHRONIZED text when synchronization completes. Pretty satisfying.

Also it’s not too surprising for a program released in 1995, but Atomic Clock handles Y2K correctly. The ACTS protocol sends the date with a two-digit year, but also sends the number of days since November 17, 1858 (MJD, “Modified Julian Date”). Atomic Clock uses the MJD only; I was able to synchronize the clock to 02/03/1980 and to 02/03/2080 without issues. (I had to pick dates between 1980 and 2099 since Windows 98 apparently does not allow setting dates outside this range).

In any case, I like the efforts they made to make a clock synchronization software look interesting. It has a lot of more or less useful options (including one to add the current time in the title bar of currently active window, which scares me)

1. I figured out which protocol the program was using by searching the phone number of the NIST time service. I also found this paper with a full dump of the protocol, which was pretty useful.