30 Oct
2019
30 Oct
'19
3:50 p.m.
On Wed, Oct 30, 2019 at 2:50 PM Zane Healy <healyzh at avanthar.com> wrote:
I would think that Multics is well inside the cctalk purview. There are
several Multics knowledgeable people lurking on this list, and if we can't
answer a question, we know people who can. Ask away...
-- Charles
On Oct 30, 2019, at 2:35 PM, Charles Anthony via
cctalk <
cctalk at classiccmp.org> wrote:
For the dps8 emulator, I wrote (for expediency) the I/O code to complete
immediately. When the CPU executes an I/O instruction, the I/O is
completed
and the interrupt posted before the next
instruction is executed. As the
emulator was (at that point) single threaded, there was no performance
reason to do otherwise, and delaying interrupt delivery was additional
code
that I didn't want to write and debug. The
consensus in the Multics
community was that this was *probably* OK; the interrupt structure was
robust and the interrupt handling code well written, and should be able
to
cope. But everytime a runtime failure occured,
the question popped up: is
zero-latency I/O the issue? I ended up adding code to delay interrupt
delivery as a run-time configuration option so that that possibility
could
be checked.
The XKCD is dead on for me. I have had that conversation.
-- Charles
If you?re on this list, does this mean this is a good place to ask Multics
questions? :-) Yes, I have a couple.