What time is it? Your C64 knows!

The userport on your C64 is a great gateway to the outside world.  Even today, hobbyists use this port to connect their trusty breadboxes to the outside world, far beyond the office space or living room where it once was limited to (a great example is the CommodoreServer project, which basically brings Commodore computing to the ‘cloud’, using the fantastic Comet64 modem).
But also in the 80s, some people looked to the skies and ‘tuned’ into the airwaves…

One such example is the ACC64 time module made by Conrad Electronic.  With this module (which plugs into the userport) you can tune your C64 to the DCF77 longwave time signal, broadcasted from Mainflingen, about 25 km south-east of Frankfurt am Main, Germany.

The transmitter is operated by Media Broadcast GmbH, on behalf of the Physikalisch-Technische Bundesanstalt, Germany’s national physics laboratory and has been in in service as a standard-frequency station since 1959.
The 77.5 kHz carrier signal is generated from local atomic clocks that are linked with the German master clocks in Braunschweig. With a relatively-high power of 50 kW, the station can be received in large parts of Europe, as far as 2000 km from Frankfurt (and further away depending on signal propagation and local interference.

With the module plugged into the C64, after about 7 minutes (the time the it needed to align itself fully with the signal), your applications could make use of this very accurate time setting.

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