26 Feb
2003
26 Feb
'03
2:04 p.m.
On Wed, 26 Feb 2003, Christos Papachristou wrote:
A few questions from a newbie:
I have installed 2.9BSD on a microPDP11/73 with an RD52, using the MSCP
version of Jonathan Engdahl. After startup the kernel
indicates 160kb of memory .I am not familiar with such an old unix to
find out the details but I understand it as 256k minus the kernel. The memory
is M8067-LF i.e. 512k Qbus. Does this mean that the system can't see the
rest of it and that I have configure/recompile the kernel?
The system seems anyway to run fine.
Are you sure it's reporting bytes, and not words?
I haven't seen an operational PDP with UNIX
before this,
so I can't judge its speed. When in single user mode it seems to
me that it runs "fast". However upon entering multi user mode the speed
drops dramaticaly. I have not yet compiled in the 8 port multiplexer
(DHV11-A), so only the console is functional and thus no gettys are
loaded. So ,why is there such a change in speed? Does the multiuser mode
just rise the nice value of the console tasks?
There shouldn't be a big difference in speed. Are you starting some heavy
demons?
Some information on the system. It is a KDJ11-B (M8190
-no suffix) i.e. an
11/84. So, the label on the system says microPDP11/73 (in an BA23 enclosure)
the cpu is an 11/84 (if the FPU socket is the DIP-40 slot then it is
unused), and the 2.11BSD second stage boot (version from vtserver) I
have tried indicates 11/83. The memory is after the CPU and is Qbus (M867-LF).
If I have understood what I have read in the list, this must be a mixed
system that could use PMI memory, but just uses Qbus?? What exactly is my
system?
There exists a specific 11/73 CPU card, but we'll ignore that for now.
The 11/73, 11/83 and 11/84 all use the same CPU card.
The differences are in other areas, and cannot always easily be detected
by software.
The difference between an 11/73 and 11/83 is if the system have Qbus
memory or PMI memory. The difference between an 11/83 and 11/84 is if the
system have the KT84 (or whatever the card is called, my memory fails me
at the moment) Unibus map, which is a Q-bus to Unibus converter along with
the Unibus map required. The CPU is always on a Qbus, but in the 11/84,
nothing but CPU and PMI memory is on this bus.
Moreover the MSCP controller (M8639 YP i.e. RQDX1)
the serial port multiplexer(M3104 i.e. DHV11-A) and the memory are Qbus while
the cpu board is indicated as Unibus in the field guide. Can these two bus type
s be mixed? (If yes , i would be tempted to abuse the dead VAX11/780 in the
basement. Can this be done?).
No.
As stated above, the CPU card is actually always Qbus. In the 11/84 you
have a bus adapter to connect the Unibus.
Anyway, I thought that the best choice of
a UNIX for it since it only has an RD52 woulbe 2.9 BSD with MSCP support.
Was this a good guess?
Yes, since you probably don't want to pay a lot of money to Mentec for one
of their OSes. 2.11 is much nicer, but you'll want more memory and disk
space for that.
Johnny
Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: bqt(a)update.uu.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol