First computer with real-time clock?

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Fri Jul 30 16:43:41 2004

> The standard "clock" was the KW11-L -- just an interrupt tied to the
> mains frequency. That was a very common option in early machines and
> became a builtin feature of the CPU assembly in later ones.
>
> Some systems, for example those used in real time control, might have
> a KW11-P -- which lets you program the interrupt rate from a choice of
> three input oscillators (100 kHz, 10 kHz, and mains, if I remember
> right) along with a programmable divider. The 11/20 on which I
> learned in the college physics department had such a beast, and I
> added support for it into RT11 BASIC.

I know both of those cards, along with the DL11-W (which essentially has
a KW11-L built-in), the MNCKW (MINC clock module, somwwhat similar to the
KW11-P, the KW11-K (IIRC that's a dual clock card with some nice
features), and so on. I think I have prints for all of them too.

However, I don't think this is what Sellam meant by 'real time clock'. I
think (and please correct me if I'm wrong) he was talking about a
Time-of-Year clock type of thing.

> Finally, there's the KW11-C which is what I was trying to remember.
> That is a TOY clock. See

Ah, now that one I've not come across.

-tony
Received on Fri Jul 30 2004 - 16:43:41 BST