🚀 go-pugleaf

On Wed, 06 Jan 1993 21:28:51 EST, you said:
> Are there any implementations of NTP available for IBM mainframes
> and for PC's running OS/2?
>                                                         -- Steve
> -------

Steve:

I assume you mean for IBM mainframes of the S/390 genre.  On those,
the 'sysplex timer' may provide the needed facilities.

On *all* S/360, S/370, 303x, 43xx, 308x, and 309x boxen, you had to hit
the 'TOD ENABLE' switch in order to let the operating system actually
modify the clock. This is a *HARDWARE* interlock implemented in the
processor controller.

AIX/370 (and presumably AIX/ESA) will run NTP OK, because they access
the clock via the 'gettimeofday()' call.  Unfortunately, MVS is a
lost cause, because once you hit TOD ENABLE during IPL, the value
returned by a Store Clock instruction is pretty immutable.

I have no information on what effect the S/390 Sysplex Timer has
on all of this - it may remove the hardware interlock restriction
and allow software tweaking of the TOD clock.
--
				Valdis Kletnieks
				Computer Systems Engineer
				Virginia Tech