IM> Is this true of _all_ versions of OS/2, that they all use the RTC for 
 IM> for their TOD clock? 

On a PC, what else *can* they use ?

Indeed, you'll be hard pressed to find *any* general purpose operating system
on any platform (apart from very old versions of DOS) that *doesn't* use
real-time clock hardware for its system clock.  

Even operating systems such as Xinu use RTC hardware of some sort.

 IM> Is the 2079 a C thing?

No.  The limits of 32-bit implementations of the C language and the C++
language are 2038-01-19 and 2106-02-07, respectively, depending from whether
the underlying type of `time_t' is signed or unsigned.

The limits of 64-bit implementations of the C language and the C++ language
are somewhat higher.

The year 2079 limitation is due to the "windowing fix" employed to solve the
problem that the PC's RTC chip in most PCs does not update the century byte in 
NVRAM when the year byte rolls over from 99 to 00.  The original RTC chip that 
was used didn't *have* a century byte.  On most PCs the area where the century 
is stored is not one of the RTC registers, but is just an ordinary NVRAM area. 
 The windowing fix works on the assumptions that years 80 to 99 are in the
20th century and years 00 to 79 are in the 21st century, and patches the
century byte accordingly.

Of course, this is a textbook case of a software bodge to work around a bad
(or at least exceedingly shortsighted) piece of hardware design.

 ¯ JdeBP ®

--- FleetStreet 1.22 NR