First computer with real-time clock?

From: Tom Jennings <>
Date: Thu Aug 5 15:48:10 2004

On Tue, 2004-08-03 at 07:13, William Donzelli wrote:
> > There's a SAGE manual on-line in Al Kossow's website (under "ibm").
> > I skimmed through it, looking for a discussion of time sources. Saw
> > none, much to my surprise. I suppose it might come embedded in the
> > radar data stream, or something like that.
> No, the streams were just digitized radar video.

Yeah, no kidding! Umm, people raised in the Beige Box era would be
shocked to read about data display in first-gen machines.

A typical high-tech radar display was often done by:

* analog voltage vs. time data delivered from radar receiver to display;
* the CRTs deflection yoke mechanically rotated in sync with the radar
dish via Selsyns & servos;
* map overlays, if any, were either transparencies applied to the CRT
face, or electronic ones were a lucite mask over another CRT, complete
with rotating yoke in sync with the main display, and a phototube that
picked up the "map" outline on the lucite, and summed the "map" voltage
in with the radar analog data;
* text markings were not done by computer (until later) but with special
CRTs called "charactrons" or typotrons, driven with shift-register
memory. (The equiv. of one line of text would be a whole rack of tube

Aint not data here.
Received on Thu Aug 05 2004 - 15:48:10 BST

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