R. T. RUSSELL

Free GNAT Clock screensaver for Windows

Modern dial, Classic hands

You've probably seen analogue clock screensavers - there are hundreds of them. But what they nearly all have in common is that they look nothing like a real clock! The free GNAT Clock screensaver downloadable from this page is different: it looks exactly like a real clock - you could easily believe that it was a TV picture of a real, working, mechanical clock. On the right is a screen shot to give you the idea (the actual screensaver image is twice this size, i.e. four times the area).

The hands are drawn using high-quality anti-aliasing, so there is nothing to betray their 'digital' origins. The minute and hour hands also move smoothly and continuously (unlike some ridiculous 'analogue' clock simulations where the minute hand moves only once per minute, so the clock appears to be, on average, half a minute slow!). The hands even cast shadows on the dial.

Settings dialogue

You can configure the screensaver using the Settings dialogue shown here. The screen shot above corresponds to the 'Modern dial, Classic hands' option illustrated. You can select the second hand from five options:

None	There is no second hand.
Step	The second hand 'jumps' instantaneously from one second to the next - not very realistic!
Deadbeat	The second hand moves intermittently, but smoothly, like a perfect mechanical clock.
Recoil	The second hand behaves like an old clock with an underdamped 'recoil' escapement.
Continuous	The second hand moves continuously, like some mains electric clocks.

The None and Step options use less CPU time than the others, so can be useful if you have a slow PC or want to make your laptop batteries last as long as possible.

Antique dial, Ornate hands

The clock face shown to the right corresponds to the 'Antique dial, Ornate hands' settings. You can almost taste the Earl Grey tea! For the most realistic effect this combination is best used with the Recoil second hand motion.

By now you're probably wondering why this clock is called GNAT (it doesn't have anything to do with biting insects!). The reason is that it mimics the behaviour of a hardware electronic clock designed in 1989 for use on the BBC's television networks (typically broadcast before news programmes), GNAT standing for Generator, Network Analogue Time. You can find out more about it, and all sorts of other interesting information, here.

The original GNAT clock used hardware to generate a video output in the 625-line (PAL) TV standard but this screensaver is programmed in BBC BASIC for Windows.

To download the GNAT Clock screensaver click on the link below (your pop-up blocker may be activated). When prompted to Run or Save the file select Save and navigate to your normal screensaver folder (this will probably be C:\Windows\System32 or C:\Windows\SysWOW64 on 64-bit Windows). You may also want to change the file name to something more memorable, such as 'Gnat Clock.scr', but remember to keep the .scr extension. You will need admin privileges to save the file to that folder.

Download gnat.scr (170 Kb)

You should find that the GNAT Clock now appears in your list of screensavers, which you can find in the Display properties dialogue (for example right-click on the desktop, select Properties and then Screen Saver). To select your preferred options click on the Settings button. The screensaver will run under Windows 95, 98, Me, NT4, 2000, XP or Vista and does not require DirectX or GDI+ to be installed. Sorry, there isn't a Mac version.

Disclaimer: This screensaver is not designed to 'save' the screen. Displaying it for long periods on a monitor prone to screen burn is not recommended. You may wish to change your Power settings to turn off the monitor after a few minutes.