RSTS/E and PDP 11/23

From: Ethan Dicks <>
Date: Mon May 17 17:40:15 2004

On Mon, May 17, 2004 at 05:46:41PM -0400, Paul Koning wrote:
> >>>>> "Ethan" == Ethan Dicks <> writes:
> Ethan> On Mon, May 17, 2004 at 11:05:25AM -0400, Ashley Carder wrote:
> >> Has anyone ever attempted to run RSTS/E on an 11/23?
> Ethan> The 11/23 and 11/24 have a KDF-11 CPU chip, so it can't be
> Ethan> that. I would _think_ that if you could get a tape controller
> Ethan> that was compatible with whatever RSTS wants (I'd guess "MT",
> Ethan> not "MS", given the era), and you had a compatible disk
> Ethan> controller, an RLV11 or RLV12, I don't know why you _couldn't_
> Ethan> bring RSTS/E 7.0 up on an 11/23.
> Interesting point.
> Qbus definitely matters for 22 bit support -- I/O addressing is
> completely different for 11/70 (UMR and RH70 extended address
> registers) vs. Q22 (extended address registers in RLV11 etc.) But
> that issue doesn't appear for 18-bit Qbus systems. So yes, you may be
> right, RL01 may work via RLV11 simply because it looks sufficiently
> like an RL11.

Right... I was thinking of mentioning that, but didn't have a good way
to phrase it... you might be limited to 18-bit addressing on the 11/23,
but presuming you had device support, it should work.
> Ditto for single line terminal interface. Not so for muxes; DZ11 is 8
> line vs. 4 lines for DZV11.

True... but the DLV11J might be OK... if not, a few DLV11Es should do the
trick, if you want more than just the console.
> RL02 is 10 MB, that would be better... The 1982 "system/options
> summary" on shows RSTS for 11/23plus on RL02
> distribution. RL01 would be quite tight though certainly a
> handcrafted subset of the kit should fit.

Also true... we used to run RSTS/E on Unibus machines around 1984-1985
with between 2 and 4 RL02 drives (the accounting 11/24 had 4 drives, but
at least 2 of them were for payroll data, etc.) We never had RL01s at
wrk, so I can't say if it will fit, but if it does, it'll be tight.

RT-11 in 5MB is fine - I did software development c. 1987 at home on
my 11/23 (a former HASPBOX for fans of sync serial comms) w/RLV11,
256KB of RAM, LPV11/LA180, and a single RL01. I borrowed all the
peripherals from my PDP-8/a and only had to purchase the 11/23 and
the RLV11 ($400 out of pocket). Still have the machine... still one
of my favorite PDP-11s (probably because I earned several thousand
dollars with it!)

...but it's only ever run RT-11 while I've had it, not RSTS.


Ethan Dicks, A-130-S      Current South Pole Weather at 17-May-2004 22:30 Z
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Received on Mon May 17 2004 - 17:40:15 BST

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