True, but the range and station count wasn't our primary concern as we
viewed it as a kind of extended range bus.
It was a big deal to us because of the RH slot that got freed up; it you
had a ÇI and an NI, that was three out of RH eight slots before you
thought about other peripherals. There was also the cost savings
involved with not having to buy an NI plus the memory saved by not
having the NI drivers in the monitor.
I don't remember how much we cared about the money. I mean, as compared
to what everything else cost. What we /really/ cared about was that
extra RH slot and the memory. Particularly the memory, as part of it
was dedicated resident/non-swappable. Even with 3.75KW, we just never
had enough memory for users. We were always looking around how to save
memory.
That's one thing I like about having a hobbyist machine; I don't have to
care about memory, so some of my solutions are easier and faster because
I don't get hung up about the space/time tradeoff.
For example, when Kermit-20 has to put parity on a packet (which it
typically doesn't), it had to call a routine to compute the parity for
each and every single character. There is a discussion in SYSREF about
how to compute parity and what the tradeoffs were. They're interesting,
particularly when learning about the PDP-10's ISA--in short, some fine
code. I used none of them and replaced code with a halfword lookup
table and a single EXTEND instruction, MOVST.
Boom. I cut the processing time down by 1/3 and I didn't even have to
do anything nearly as clever as SYSREF.
I have run out of swap space, which appears to be limited to 20,000
pages. Don't do that. You'll pretty much hang solid. I have looked at
the issue and (sort of) remember that the current limit is 20,000, but I
think it could be expanded to 30,000 pages.
I wouldn't swear to it, but when we were a field test for 6.x, there was
some internal documentation on DECnet over the CI. I think there is
still some kind of write up on it, somewhere.
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On 5/17/24 11:19 AM, Paul Koning wrote:
It seems quite reasonable except for the fact that CI has such a limited range and
station count. It's just that it wasn't specified in any DNA spec.
paul