rewriting legacy OS for new iron

From: Ethan Dicks <>
Date: Tue Sep 14 17:54:34 2004

On Tue, Sep 14, 2004 at 10:52:08AM -0700, Lyle Bickley wrote:
> What Ed suggests would work fine. Or you can probably pick up an 11/23+ for
> less $ and it will handle RSTS/E nicely - though not as "snappy" as a micro
> 11/73 or 11/83.

In my experience, PDP-11 CPUs are much easier and/or cheaper to find than
a Qbus disk system that does not use MFM drives. I have plenty of RQDX
controllers and older drives, but a single Qbus SCSI card is usually more
expensive than the box you previously bought to put it into.

Of course, as others have pointed out, the current cost for an RD54 (~150MB)
MFM drive (Maxtor XT-2190) is high enough that if you don't already have one,
you might as well consider a Qbus SCSI card. Best to stay away from RD53s
(Micropolis 1355 w/R7 jumper added) unless you a) have a good backup scheme,
and b) like replacing drives every few years.

I remember RSTS/E on F-11 CPUs (11/24...) being kinda doggy, but we were
doing lots of compiles of our product, and using the box to test/use our
data comms products (HASP, 3780...); RSX-11/M 4.2 wasn't exactly flying
on the same hardware either. If you want to play with anything more
complicated than RT-11 on real PDP-11 hardware, I'd consider an 11/53
(KDJ-11 CPU) to be a bit better, not even counting the fact that you get
Split I&D space and can build larger programs. Yes, an 11/73 or /83
would be 'snappier', but a bit more pricey, especially over an 11/23.

I would love to find an 11/8x or 11/9x, but I'm not holding my breath. At
the moment, my fastest real Qbus -11 CPU is out of a communications server,
making it, ISTR, the same as an 11/53 CPU (with different ROMs, but I
have solved that already). It is destined to go into a BA123, perhaps with
a 3rd party disk controller.


Ethan Dicks, A-130-S      Current South Pole Weather at 14-Sep-2004 22:40 Z
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Received on Tue Sep 14 2004 - 17:54:34 BST

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