Years ago (circa 1996-1997 maybe?) I ran a MS-DOS program that showed a map of the whole earth, updated once a minute with the time, timezones, and light/dark areas of the planet, taking up the whole screen. I ran it on a spare 286 I had lying around. I think I might have even gotten the idea/program from an article on the internet.

It was a very cool program with a few different configuration options, and I think it was either free, or shareware, available on the internet. For the life of me I can't remember the name of it. It was something like World Clock or Free World Clock or something like that, but that's just a bit generic of a name for Google searches.

Can anyone identify this program?

  • 1
    Could it have been xearth? Commented Oct 8, 2021 at 2:22
  • @GregHewgill No, but that program is the right idea and has similar functionality. This was almost certainly a program native to DOS. Commented Oct 8, 2021 at 2:40
  • 2
    I remember screensavers that did this. That might be a different search term for you.
    – Chenmunka
    Commented Oct 8, 2021 at 10:02
  • 3
    UFO: Enemy Unknown? :P
    – marcelm
    Commented Oct 8, 2021 at 19:08
  • 1
    @marcelm Endgame: Singularity, surely. Commented Oct 11, 2021 at 11:07

3 Answers 3


The one I know is GeoClock, though it looks like its website is no longer in operation.

Screenshot of GeoClock version 7, with a timestamp 8th of October 2021, 20:04 EDT

It can still be found in Simtel archives, along with extra maps. You can also see an older version in action on the Internet Archive.

  • I recall having a program such as described, before I got Windows, and the name seems familiar.
    – supercat
    Commented Oct 8, 2021 at 15:35
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    It seems to require a 387, where the asker mentioned a 286 machine. Although the recollection may be mistaken, so this may still be it. Commented Oct 8, 2021 at 18:25
  • 3
    This is it. I'm not sure about the 387.... maybe that's a later version? I do recall it used a lot of CPU. IIRC 387 co-processors were somewhat rare, so I expect there was a version that runs on straight integer math. Commented Oct 8, 2021 at 23:17
  • 3
    Earlier versions of GeoClock don’t require a 387 and run fine on a 286 without an FPU. Commented Oct 9, 2021 at 5:20

This might be Home Planet, developed by John Walker. The second release was published as freeware in 1994, and ran on Windows 3.1. (I haven't been able to track down information about the previous version.)

Its main screen (which is also usable as a screensaver) shows the day and night areas of the earth's surface, albeit without time zones:

Screenshot of Home Planet

(screenshot cropped from https://www.fourmilab.ch/homeplanet/samples/help2.gif)


It probably wasn't this: Amateur Radio Clock. But this type of clock application is popular with ham radio operators.

What you're describing sounds a lot like a software version of a Geochron. These are mechanical maps of the world with light and dark bands that move across the projected planet.

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