First computer with real-time clock?

From: Tom Jennings <tomj_at_wps.com>
Date: Sun Aug 1 16:03:27 2004

On Thu, 2004-07-29 at 13:20, Vintage Computer Festival wrote:

> I'm more interested in a clock/calendar: something that could be polled
> and produce the local time and date.

But but... this isn't an obvious statement, even... even 'stand-alone
battery-backed chips producing BCD date & time in English' require
interpretation (interface protocol, output, etc) schematically no
different than the simplest timer tick, via interrupt or mainline code
IO or memory poll (or hell HALT). Then there's light-to-dark-grey chips
that produce isochronous events, even timedate specific, in all sorts of
intermediate forms, seconds since FOO, etc. Every hardware programmer
has coded dozens. I did one/many for CP/M (in my homemade command
interpreter) and MSDOS, etc.

> I'll bet an interesting history lurks behind such a seemingly simple topic
> (real-time clock calendar deployment in computers).

Oh it's certain! Few things are more taken for granted but hard to pin
down.


My favorite on the opposite end, is a random bit stream produced by
using the pulses from a geiger counter (and associated radioactive
material) to clock a long shift register. It's well-discussed, but I'm
not sure anyone ever produced one.
Received on Sun Aug 01 2004 - 16:03:27 BST