[time-nuts] 60Hz mains clocking in computers

[J. Forster]

I'm not so sure about the Nova 1200. I think all the Novas had the RTC was
on a standard I/O board, along with the serial interface, PTR, PTP. I
remember two crystals, one 16.000 KHz for the clock. The other was for the
Baud Rate generator, somewhere about 1 MHz. A minimal system had 3 cards
(CPU, Memory, and I/O)

-John

=============

> Talk about dusting of the old brain cells.
> I seem to remember that the PDP 11/23s did indeed allow the use of the 60
> hz
> as an interrupt for precision timing if that can actually be said. The
> data
> general nova 1200 also. Boy thats exposing ones age.
>
> On Sat, Dec 12, 2009 at 8:29 PM, Colby Gutierrez-Kraybill <
> colby at astro.berkeley.edu> wrote:
>
>>
>> I'm trying to get to the bottom of whether or not any computing
>> equipment
>> made around the advent of UNIX systems (or any time-slicing system) used
>> the
>> mains cycles of 60Hz as phase lock for the internal system clock.  My
>> guess
>> is that perhaps they did not as the computing logic is DC based, but, I
>> have
>> memories of using an 68000 based UNIX system that I thought had its
>> internal
>> clock based off of the 60Hz mains...  Not sure the vendor anymore.
>>
>> Thanks,  Colby
>>
>>
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