DEC RX50 Test Disks

Pete Turnbull pete at
Thu Mar 3 06:55:35 CST 2005

On Mar 2 2005, 20:25, Christian R. Fandt wrote:
> I have a set of five RX50 floppies which contain various service
tests. I
> have not yet discovered what machine/CPU these work upon. Could
> point me in the direction of how to interpret the seven-character
> numbers?  All have a copyright date of 1983. They are as follows:
> CZUFDB1 (disk part # BL-T540B-M1 "USER TESTS")
> CZXD1B1  (disk part # BL-T541B-M1 "FIELD SERVICE TESTS 1")
> CZXD2B0  (disk part # BL-T542B-MC "FIELD SERVICE TESTS 2")
> CZXD3B0  (disk part # BL-T565B-MC "FIELD SERVICE TESTS 3")
> CZXD4B0  (disk part # BL-T583B-MC "FIELD SERVICE TESTS 4")
> Are these some version of XXDP? They came with the MVII and

They're the standard XXDP disks that came with a microPDP-11 -- they
were probably supplied with your microPDP-11/73 when it was new.
 They're no use for a VAX.

Aren't these the same disks you asked about last May?  I posted a
listing of the directories then.

There is a manual for XXDP, but I don't have it (unless it's buried in
my microfiche somewhere, which I don't think it is).  However, I put my
notes and extracts of the help files on my web page a long time ago,
and you can still find them here:

(same contents, just different file formats).

Those will allow you to work out what most of the files do.  There's
also a partial list at

Al and Henk had a discussion some time ago about scanning the documents
(program-specific instructions and listings) for each of the
diagnostics.  Each one is normally known by a name like ZRQBH0, or more
often just ZRQB, where the first letter refers to the processor type,
the next 2 to the device, the fourth to the test number.  The last
letter and digit are the revision and patch level -- so ZRQBH0 is to
run on any processor ("Z"), to test some part of an MSCP disk system
("RQ"), test "B" -- actually it's the formatter for an RD51 or RD52 on
an RQDX1 or RQDX2 controler (ZRQC is the corresponding formatter for an
RQDX3).  It's therefore slightly unfortunate that Al indexed his by a
different scheme, but not too hard to find what you want (if it's in
his archive).  Look at

for some scans.  The initial "C" on some of the names refers to the
media it was supplied on.  It's not really part of the name.  Henk has
summaries of some that are relevant to his interests, on his web page
at  (see the menu entry for XXDP on the left)

which are fine to get you going, but many of the disgnostics halt on
varous errors, and you often need the listings to see what caused the
halt, or to do more than simple tests.

Pete						Peter Turnbull
						Network Manager
						University of York

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