First computer with real-time clock?

From: dundas_at_caltech.edu <(dundas_at_caltech.edu)>
Date: Thu Jul 29 12:44:57 2004

> On Thu, 29 Jul 2004, Andy Holt wrote:
>
> > If you mean a clock that maintains time when power is off or gets the time
> > by radio then we are probably into the micro era.
>
> Yes.
>
> But I can't imagine there was not a real-time clock (i.e. as described
> above) as at least an option for an earlier computer system.

Certainly during the era of PDP-11s, DEC had a number of possible solutions,
though our lab never used them. Instead we used the Digital Pathways TCU
series. For example, see the manual for a Unibus board:

<http://dundas-mac.caltech.edu/~dundas/retro/tcu-150.pdf>

We used these in several 11/55s:

<http://dundas-mac.caltech.edu/~dundas/retro/tcu-trans.pdf>

There were also Qbus versions:

<http://dundas-mac.caltech.edu/~dundas/retro/tcu-50.pdf> and
<http://dundas-mac.caltech.edu/~dundas/retro/tcu-50qd.pdf>

See this for more information:

<http://dundas-mac.caltech.edu/~dundas/retro/tcu-lit.pdf>

Granted this was probably well after the IBM 650 (I'm not familiar with that
machine).

Hope this helps.

John
Received on Thu Jul 29 2004 - 12:44:57 BST