On Mon, 4 Jan 2021, Peter Jeremy wrote:

> Alternatively, my understanding is that the Unix epoch changed on
> several occasions in the early days.  Presumably the knowledge of how to
> achieve this hasn't been lost.  (Though actually performing an epoch
> rollover may be more difficult today).

My understanding is that it's been 1st Jan 1970 since at least Ed5, if not
Ed6.

> I suspect that 2038 may actually wind up being more serious than Y2K
> because there are now far more embedded systems than there were then but
> it's not clear that the designers of those systems learnt the lesson
> from Y2K.  A few weeks ago I tried to count the number of CPUs in my
> bedroom, bathroom and study - my best guess is around 2 dozen.
> Admittedly, I think relatively few of those will be concerned about
> epoch rollover.

The only systems I have that would care would be the various computers,
and they are all NTP-synced (except the NBN modem/router takes its time
from T$).

> Plus 2038 is merely one epoch.  Someone mentioned the Microsoft epoch
> rolling over in 2048.  Between those two, the IBM S/360 epoch rolls over
> in 2042 - the Z-series appears to have glued another 8 bits onto the MSB
> end of the TOD clock but that won't help all those S/360 and S/370
> binaries that are still being run.  And they are just the well- known
> ones.  I expect that there are lots of embedded systems running custom
> epochs with weird rollover dates.

Well, I don't care about the M$ epoch, and at 86 I might even get to see
the world come to a grinding halt :-)  Of course, I may be reliant upon M$
systems in hospitals etc...

Interesting story about the S/360 though.  As a side-issue I wonder how
many COBOL programmers will still be around to maintain all that payroll
software etc?

-- Dave, who's kept his COBOL knowledge a secret in every job