[TUHS] DECtapes under the UNIX room floor

[Warner Losh via TUHS]

On Wed, May 6, 2026, 4:49 PM Erik E. Fair via TUHS <tuhs at tuhs.org> wrote:

> I have a tickle in my memory that the Unix V7 (or 2BSD?) answer to a lack
> of battery-backed ToD/ToY RTC was using the last modify date of inode #2 in
> the root filesystem as "close enough for government work" precisely because
> that'd be the last one modified in a clean shutdown, and definitely better
> than starting time_t zero (epoch: 00:00 Jan 1 1970 GMT).
>

BSD does that to this day.

Warner


There was also the issue for many years of having to kill cron before doing
> a big delta time change: cron would wake up suddenly hours or days later
> than it thought the last time it had run, and would spawn all work it
> needed to run to "catch up" ...
>
>         Erik
>