🚀 go-pugleaf

From: Mike Ciaraldi  <ciaraldi>


I asked about this a year ago and got some good ideas, so
here goes again...

I know someone with the following system:

PDP-11/23 CPU
256K RAM board
2 DLV-11J 4-port serial boards
Paralel printer board
RLV-12 disk controller with 4 RL02's
5-inch backplane supporting 18-bit addressing.

All running TSX (which we run by first booting RT-11).
This system currently supports five terminals,
but cannot really run with more than 3 simultaneous users.

He'd like to expand the system for more users
and higher speed.  We may want to do this in stages.

From what I've heard, we should be able to go to more
memory with our 11/23 (not an 11/23 Plus).  The original
(1981) DEC manual says it's limited to 256K, but the
current one says it can go to 4 Meg.
However, we would have to either replace or modify the 
backplane to allow 22-bit addresses to be sent to the boards.
Also, our present memory board would not work, as it
only looks at 18-bit addresses.
The disk controller will work OK with 22 bit addresses.

Does this sound right?

From a software point-of-view, what do we have to do?
I had to redo the TSX sysgen to enable the additional terminals
last year.  I don't see where TSX is told how much memory
you have.  Does it figure it out automatically?  Do we
have to redo the   RT-11 Sysgen for the extra memory?
Is that hard? (never did one for RT-1 before).

For the future, we may want to go to a faster processor,
e.g. an 11/53  or 11/73.  Do we have to worry about this
when we buy our new meory board?  I know PDP-11's adjust
to the speed of memory automatically, but I wonder if we
have to specify especially high-speed memory or something
to ensure we don't have a bottleneck in the future.
If we have to buy new memory to expand anyway, we miht
as well buy some that would work with a new processor too.

Again, I don't see where TSX cares what model processor
we have.  Are there any differences? (e.g. memory managment?)
Again, do we have to redo the TSGEN and/or the RT-11 sysgen
when we change processors?

Finally, how many users could we realistically expect to
run on an 11/73?  They would mostly be running accounting
software, no eiting or compiling.  As I said, the
11/23 with 256K poops out at 3, mainly due to 
lack of memory to run the jobs.

I appreciate any ansswers, commets, or suggstions.
Incidentally, theey may also bite the bullet and buy
a Microvax II instead of upgradingthe present system.

Mike Ciaraldi
ARPA:    ciaraldi@rochester
Usenet:  seismo!rochester!ciaraldi