First computer with real-time clock?

From: der Mouse <mouse_at_Rodents.Montreal.QC.CA>
Date: Thu Jul 29 11:03:12 2004

>>> If you mean a clock that maintains time when power is off or [...]
>> 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.
> VAX Architecture Reference Manual requires every VAX to have one, and
> they all indeed do starting with the 11/780.

If you mean the ICCS/ICR/NICR stuff, that's not as described above - it
counts only when power is on, and even then only when told to by
software. If you mean the TODR, that _is_ as described above, but
_not_ all VAXen have one; the KA630 documentation, at least, describes
the TODR as class 3: writes ignored, reads always return 0. (The KA630
does have a clock chip which can be used to do similar things, but it's
not a VARM-described mechanism - at least not my edition of the VARM.)

For the purposes of the discussion that produced this thread, though,
the VAX does count, since the flagship VAX, the 780, did have it.

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Received on Thu Jul 29 2004 - 11:03:12 BST