Reverse-assembled PDP-11 Diagnostic Monitor

Software
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Ian Hammond has reverse-assembled the XXDP PDP-11 diagnostic monitor and posted his efforts for all to see:

XXDP is a minimal disk operating system from DEC for the PDP-11 that was used to host their diagnostic programs. It provides a simple, flat filesystem interface (using the DOS-11 on-disk structure) and a binary loader, as well as a monitor interface for querying the fileystem, running diagnostics, and some configuration tasks. The DOS-11 filesystem is an artifact of a pre-RT-11 real-time DOS for the PDP-11 that was almost totally supplanted by RT-11. Like most DEC PDP-11 operating systems, it uses a 6.3 filenam.typ file name format encoded in RADIX-50 (digits, capital letters, $, and %).

Ian’s disassembly includes substantial commenting and cross-referencing, and looks a lot like original source for MACRO-11 might have. It’s really a work of art.

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Many thanks. Originally I just wanted to know how it worked, but as I got to know it I saw a system that deserved a bit of love and to not be forgotten. Seeing the code slowly emerge was like watching a garden grow. Since uploading the disassembly I’ve converted XXDP to use RT-11’s file system instead of the file system it inherited from DOS-11. Ian.

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Very cool! Working with the DOS-11 filesystem for XXDP has always been a bit of pain for me, because of having to use foreign filesystem drivers to access it. I look forward to seeing that project!

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Hello all ! I have a few (perhaps 10) manuals with listings of DEC pdp11 diagnostics. Eventually I can scan and share them io anyone is interested.
Also, I will like to contact Ian Hammond.

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Please do, if they are not already available! If you can scan them at a moderately high resolution and you upload the images to the Internet Archive using their book upload instructions, their software will stitch the pages into PDFs with associated text content created by character recognition.

Check bitsavers and the Internet Archive to see if they’re already scanned and available; many such manuals are, but not all, and some of the scans are of a quality that leaves something to be desired.

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I will do that, but in the meantime I am posting the titles of what I have for anyone interested.

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a first batch:
“DEC/X11 11/70 monitor library”; DEC, 3-1977; MAINDEC-11-DXQLJ-D-D; 158p;
“DEC/X11 options library #2”; DEC, 10-1977; MAINDEC-11-DXQLI-G-D; 174p;
“DZ11 & Line async MUX test”; DEC, 3-1977; MAINDEC-11-DZDZA-1-0; 133p;
“DEC/X11 2040 System secondary front end module library”; DEC, 6-1977; MAINDEC-11-DXQLK-B-D; 127p;
“DEC/X11 LSI-11 Options Library”; DEC, 8-1977; MAINDEC-11-DXQLO-C-D; 106p;
“VT50A, B, H, 52 acceptance test”; DEC, 1-977; MAINDEC-11-DZVTC-D-D;

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