In <[EMAIL PROTECTED]>, on 04/21/2006
at 10:48 PM, "John S. Giltner, Jr." <[EMAIL PROTECTED]> said:
>I guess my wording is a bit unclear. I did not mean to imply that
>any OS does actually support this, but I meant to imply any OS could
>be written to support it.
The OS can't support hardware that isn't there. And BTW, the TOD clock
is only part of the timing facilities on zSeries.
>Why?
Because the various computers don't have the same timing facilities.
>and last time I checked PC's do not have TOD's
Which is why you can't do on a PC those things dependent on a TOD
clock and comparator.
>Again, logically, aren't they are providing the same function.
No.
>Telling the OS what time it is?
No, that's one function, and not the most important one.
>Some OS's have deciced that they will get the time when they are
>started and keep track of it themselves, other OS keep going back to
>the "hardware" clock. Is this not true?
No. An OS is limited by the hardware at hand. Deciding not to exploit
hardware is an option, but when the hardware is missing then deciding
to exploit it is not an option.
>Well I beleive that I have been looking at it from a logical, not a
>technical point of view.
The Devil is in the details. I don't believe that it is possible to
look at it from a logical point of view without first understanding it
from a technical point of view.
>A TOD clock is a clock, just like a RTC, and
>just like the watch on my wrist.
No.
>Or am I wrong, does a TOD clock provide some other purpose that
>providing the time?
Yes. It also provides notification and synchronization facilities.
>I don't beleive the person that started this originally was looking
>for the technical details of exactly how things worked. I beleive
>he was looking for a general/logical comparsion.
I believe that he was looking for a *correct* comparison. The timing
facilities on the PC are fundamentally different from those on
zSeries, and an OS like Linux has to abstract away those differences
and provide portable services rather than access to the underlying
hardware.
--
Shmuel (Seymour J.) Metz, SysProg and JOAT
ISO position; see <http://patriot.net/~shmuel/resume/brief.html>
We don't care. We don't have to care, we're Congress.
(S877: The Shut up and Eat Your spam act of 2003)
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