resurrecting a PDP-11/10

From: Ethan Dicks <>
Date: Thu Feb 27 14:34:00 2003

--- Fred Flintstone <> wrote:
> Yes, I guess I should call it a 11/05. despite what is clearly printed on

> the console.

They are the same thing except for the label. The 11/04 and 11/35 came
in two flavors also - BA-11 with the boards vertical, or in the shorter
box with the boards horizontal.

> If I get the RK05J disk cleaned and ready to go, and toggle in the
> bootstrap and the disk loads, do I need to manually start the O/S at
> some location?

If you toggle in the bootstrap and the disk loads, you are *running*
the OS (if the pack was bootable).

The purpose of the bootstrap is to provide just enough code to reset the
controller (sometimes) and load block #0 into memory location 0 and
jump to the right place in it to make _that_ code do something useful.

> I believe the M873YA Bootstram ROM is capable of booting the RK05,
> but I don't know what would need to be done next (I believe 773010
> will boot the RK05)

If you have a bootable pack spun up in drive 0 with all the right lights
on and you jump to the boot code address (773010, in your example), the
lights will flicker, the code in ROM will load block zero into low core and
jump to it. If the filestructure is intact and hardware is all working,
you should get a "." prompt (for RT-11). Start by typing "DIR" and see
what's out there.

> I want the PDP-11/20 to eventually be historically correct but with a
> full load of options :-)

That's a lotta cabinets! There were plenty of options that would be
appropriate for it. You might have to end up picking a configuration
out of old docs, or picking a year and declaring, "this is how a
commercial user might have had theirs equipped in 1973" or something

One of these days, I'll have enough time to restore my 11/20. I'm
still up to my armpits in 12-bit projects (like fixing an -8/e so
I can try out my "new" RK8E)

> The ultimate goal is to run adventure and Star Trek on it using the LA36
> terminal. ie. the quintessential time-wasting use of a mini-computer
> ;-)

Perfect. A laudable goal.

Given that, you may want to look into an old version of RSTS once you
are happy with the hardware. It's very BASIC-centric and there are
plenty of BASIC games from the old days... source is available on the
'net (google for "classic basic games"). I spent many hours dialled into
a RSTS machine over an LA-36 w/integral acoustic coupler when I was 10.

Star Trek and Adventure (and other games) are available for RT-11, too,
with much less system management effort.

You can also practice your RT-11 and RSTS skills with Bob Supnik's
SIMH - All the BASIC fun with fewer
cuts and pinches from old cabinets. You'll at least be able to
familiarize yourself with the software while not worrying if the hardware
is behaving.

I still recommend the real thing... it's an auditory and olfactory
experience as well. There are few options for blinkenlights and
emulators. :-(

> Of course the blinkenlights and tape operating has to be
> part of it too!

Naturally. Why have blinkenlights if they aren't blinken.
> It is interesting that my 10 year-old son asks to play Star Trek on my
> MicroPDP-11 rather than the full-motion flight simulator on the PC.

Smart kid.

Received on Thu Feb 27 2003 - 14:34:00 GMT

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