[pups] Getting a MicroPDP-11 Running

Steven M. Schultz sms at moe.2bsd.com
Tue Jul 25 13:18:29 AEST 2000


> From: Jeremy Bingham <jeremy at mail.flyingcroc.net>
> I just acquired a MicroPDP-11 from a Goodwill a couple of days ago with a

	Wow - that's a source for PDP-11s I would never have thought of :)

> RX50-A dual 400KB floppy and an RD52 31/33(?)MB hard drive, but it doesn't 
> have a tape drive. My questions are:

> 1.) What UNIXes have been successfully loaded onto these types of machines?

	I think we need just one more little piece of information before we
	can match up a version of Unix with your new machine.

	We need to know if it's an 11/23 (23+), or an 11/53 (73).   The 
	label "MicroPDP-11" was used on a number of systems.   If it's a 53
	or better then you can run any of the PDP-11 Unix systems that are
	out there.  If it's a 23 class machine then you're limited to V7
	or earlier (2.9BSD would probably fit but it would be a struggle and
	you definitely wouldn't be able to use the networking).

	Looking at the system maint register with the console ODT would
	probably be the easiest way to determine the cpu type - examine
	location 177750 (or 17777750 depending if the system needs the 
	explicit 22 bit address).  Bits 4 thru 7 tell the module type:
	5 = KDJ-11E (93, 94), 4 = KDJ-11D (53), 3 = KXJ11-C, 2 = KDJ11B
	(quad high 73), 1 = KDJ-11A (dual high board 73).   If it's a 23 the
	sys maint register probably doesn't exist.

	Another way would be to look at the module number on the spine of the
	card ;)

> 2.) Can it be done without a tape? If so, has anybody pulled it off?

	A ~32mb disk is going to be very tight for any 2BSD system.  V7 will
	fit I think.

> 3.) Are there any utilities, either DOS or UNIX/Linux/FreeBSD based, to write
> and/or format RX50 floppies?

	Hmmm, I thought John Wilson has some utilities that could do that.
	Normally you need to buy preformatted RX50 disks or have a DEC Rainbow
	(DOS) system around.

	On the other hand if the controller is an RQDX3 it is possible with
	some luck (and more hardware skill than I have ;)) hook up a standard
	5.25" Teac floppy drive.   I don't have the location of the info for
	that at hand - you might try the alt.sys.pdp11 or vmsnet.pdp-11 
	newsgroups (lots of knowing folks hang out there).

	Steven Schultz
	sms at moe.2bsd.com

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