[TUHS] DECtapes under the UNIX room floor

[G. Branden Robinson via TUHS]

At 2026-05-06T08:12:15+0000, Thalia Archibald via TUHS wrote:
> >    With `tap', the times associated with the files were recorded
> >    in pre-modern units: sixtieths of a second, from an origin that
> >    changed.
> 
> Was there a precedent for the choice of sixtieths of a second?

We may be spoiled for choice; sexagesimal goes back over 4,000 years to
the ancient Sumerians.  ;-)

It's also the mains line frequency in North America.  I don't know if
anyone's ever clocked a digital computer that slow, but some peripherals
might have stuck a rectifier on the mains and used that for a clock.

Here's an app note from Renesas for a real-time clock that works that
way.  Crystals go home!

https://www.renesas.cn/zh/document/apn/an1342-using-60hz-power-line-frequency-accurate-real-time-clock-timebase

> >    dmr
> >            Random stuff from my directory.  Most probable dates: 1972.
> >            The `paper' directory contains a version
> >            of the original SOSP Unix paper (haven't compared
> >            it with the CACM version).
> 
> This should be rendered and added to TUHS.

...and gotten into Clem Cole's hands so we can see how groff fares as
the renderer.  ;-)

Regards,
Branden
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