1 Oct
2023
1 Oct
'23
1:06 a.m.
On 2023-09-30 22:11, Paul Koning wrote:
Yeah. It's ugly. And it means any OS you want to run needs some serious
changes.
On Sep 30, 2023, at 12:47 PM, Johnny Billquist
<bqt(a)softjar.se> wrote:
On 2023-09-30 17:59, Robert Armstrong wrote:
Afraid it's going to be more complicated than that.
DEC in all it's wisdom decided to make the Pro hardware not really that PDP-11
compatible. So any OS that you want to run on the Pro will need to be rehacked in order to
make it possible.
Any "normal" RSX will not run on the Pro out of the box. Neither will any other
OS.
"Not really... compatible" is understating things. In fact, it is utterly
unrelated to a real PDP-11 except in the CPU. Everything involved in I/O, from the bus to
the peripheral devices to the interrupt system, are thoroughly different and in many cases
quite messed up. Part of the problem is that the Pro-350 uses a pile of Intel chips,
perhaps in an attempt to reduce cost, and as usual for Intel those chips have many bad
design features. The interrupt controllers are particularly nasty. Thomas
DeBellis <tommytimesharing(a)gmail.com> wrote:
Until we started using it an early version on a daily basis...
I always
kind of liked the PRO, although the "native" OS, P/OS, is not a feature. I
actually have a 380 with an NI out in the garage; I should get it out and try to install
MicroRSX on it instead. Does anybody know if there's a copy of the version with the
PRO drivers somewhere? It doesn't help that all the I/O devices (except
for CNA) are programmed I/O even though I think the bus supports DMA. Doing hard drive
I/O one word at a time is ugly, though it turns out the controller is so pathetically slow
that the CPU isn't the limitation even with that horrid design. (I found this out
when I tried to reduce the interleave on the Pro-380. No go: the standard interleave is
the best possible both for the Pro-350 with its F-11 and the -380 with the significantly
faster J-11.)
I'm almost certain that DMA is technically possible. But yeah, not used.
And yeah, the disk does very slow. Not surprised by your findings.
Johnny
--
Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: bqt(a)softjar.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol