Will's PDP-11/23 Information Page - Restoration Tools

Last update: 01/10/11

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Will's PDP-11 Documentation Corner

I got started on this cause some of my earlier experience as a student at WPI was on an old PDP-11. Living not too far from the DEC offices in Maynard, MA I began to see systems for sale at prices I could afford. I now have a reasonable collection of manuals and handbooks for the LSI-11 (Qbus), particuarly regarding 11/23 systems. I don't think knowing about PDP-11 systems is very useful today, but I'm afraid I just can't help myself...

To my knowledge (I called 1-800 Digital and Mentec in the Spring of 2000) the handbooks are now only available in private collections such as my own. However "Digital" confirmed that "LSI-11 Systems Service Manual" part # EK-LSIFS-SV was still available for $42. They would only ship to a US address, but if you want a great technical document consisting of 3 volumes with 1168 pages of jumper and register info on LSI-11 modules) its well worth ordering. I include a summary of the table of contents in one of the documents below in case you think you might be interested.

If for some reason you have decided to try to save one of these systems from the trash bin, you may need some help. If you are in this group, you should definately visit some of the links above and watch the vmsnet.pdp-11 newsgroup. I put together the pages below to contribute to the public knowledge base. Hope someone finds them useful or at least interesting.

Note that these may contain errors, please let me know if you spot one. People often successfully request dip switch settings on the newsgroup. If that fails let me know, maybe its the next board I should document, then again don't hold your breath its time consuming and BORING.

I also have some documentation on more obscure things. In general I haven't bothered to put it in machine readable form, but maybe able to give helpful hints where required. Amoung other things I have some documentation on Plessy System boards for 11/03 type systems. I am also the proud owner of three Emulogic emulators. These let me develope 6502 and 68000 code on a PDP-11 system, cool. These came with user docs or if anyone wants replacement parts I can give you a deal.
The systems above also came with a Computrol Megalink network which turns out to be an RF modem link to an RSX host. If you happen to have a Computrol board set (30-0096 and 30-0097), I now have some documentation which came with the Emulogic system above.

Thirty some years ago my dad also bought a Sigma RL02 emulator package. It is a board that plugs into the QBUS and emulates an RL02. The Sigma board sends SASI (I'm told this predates SCSI) format signals to an Xebec formater that controls an MFM disk drive. We had problems with this system (currently in my basement), but it still runs on a good day. I think the MFM disk we had was the problem, and have been much happier since switching to real DEC RL02's. However, today its no easirer to replace an MFM disk than an RL02 so we are in trouble either way!

I scanned the majority of the Sigma SDC-RLV12 manual for someone who wants to try to use this to talk to current SCSI disks. I'm putting what I scaned on line since I've got it, and cause it contains information about the standard RL02 registers. I skipped portions dealing with other formaters/disks, but have the original manual. I also have the Xebec formater manual if anyone needs this info.

Will's MSDOS Utilities for PDP-11

BECAUSE THESE PROGRAMS ARE DISTRIBUTED FREE OF CHARGE, THERE IS NO WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION. Everything available on this web page has been compressed with my old friend LHarc. They are self expanding archives, depending on their size it may be a *.exe or a *.com file. Execute the program in the directory of your choice and the files listed in the documentation will be extracted. I suppose I should switch to gzip, but I've always used LHarc on my MS DOS systems. During the summer of 2000 I completed a beta release of an MSDOS program which emulates a PDP11 running the RT11SJ monitor. If interested look at the RTEMU documentation.

I wrote some 16 Bit MSDOS C code for RT11/PDP11 Utilites in 1994 and uploaded it to Compuserve's PDP11 area. That has disappeared, so now I'm adding the collection to my own page. In the process I enhanced boot detection for the TU58.exe program. Its now all in a self expanding LHarc archive. This is a collection of methods to obtain and manipulate PDP11 disk images on a PC. For a better description check out the limited documentation.
Note that one of the utilities, TU58, which allows a PC to emulate a TU58 tape system is a useful archive tool. The TU58 (and its emulation) is also a very useful troubleshooting tool as one can use them to boot a pdp11 via a serial line, ie your printer port, if your disk drive malfunctions. I recently found a BSD Unix equivalent. This Unix code is also available from dbit. I've done some work on a Linux port. With my modifications the program runs in the Linux environment and emulates a TU58 when talking to a PDP 11/23, but has problems with E11. I've talked to John Wilson about this, and am not sure if the problem is in the emulator or a side effect of E11's serial port handler.

I don't expect there to be a BIG demand for TU58 or disk utilities above, but you are welcome to what I've done. I recently ported RTEMU and my disk utilities to Linux and can provide an executable on request. I was also very interested in the DEC Rainbow for a while. It runs an early version of MSDOS and uses RX50 disks. I found the Rainbow very useful for creating bootable RX50 system disks with the tools above. I found this much more reliable than most of the various utilities that attempt to use a conventional PC's 5.25" drive to create an RX50. If curious contact me. I just recently (2001) discovered that John Wilson's PUTR program can reliably create RX50 disks on current 5.25" PC drive. For most purposes I think PUTR is the program of choice (I can't get it to work with TU58 images of XXDP).

Recently I had a couple machines start to act erratically and got interested in debuging on an 11/23. I think all PDP-11s came with ODT microcode which I am just finding (a bit late in life) to be a useful tool. I put together a couple pieces of old code and generated what I think may be a useful tool for testing sick systems. One uses a PC's serial link to replace the PDP-11 console terminal and talk to ODT. It doesn't do anything you can't do by hand if you are patient, but automates some things for you if you aren't. In particular it will scan the IO page and if desired create a record of the valid locations. I am working on a little database which would attempt to identify installed componets from the IO page addresses, but this is still under development. This interface will also upload and execute small program segments (such as bootstrap routines) to test your system. Read more about this package in the documentation file or download the self extracting LHarc archive containing the BETA version of the programs and documentation. Note that there is a separate test library archive containing test and bootstrap code which one can upload to your PDP-11 via ODT. See the current library contents and history. I hope to expand this library, but will need some assistance validating test code for devices I don't have in the basement.

If you are an old hand with PDP system you are probably aware that the standard DEC diagnostic tool was the XXDP collection of diagnostic programs. With my various systems I have acquired several versions of this program, but always find it rather cryptic to operate. I've put together what I do know in a preliminary XXDP User Guide. This includes information on how to create bootable subsets of the full distributions on smaller volumes. Last time I looked (spring 2000) XXDP version 2.2 and 2.5 distributions were available in *.gz format as RL02 image files, respectively 3.2Mb and 3.6 Mb.

If you have a sick PDP-11 I recommend the following trouble shooting guide. Ákos Varga has a very readable description of the bus architectures. Various archives have boot straps and source code for testing PDP systems, but I found the U-NET source code very useful.

will kranz,
Jun 21, 2017, 5:07 AM
will kranz,
Jun 21, 2017, 5:12 AM
will kranz,
Jun 21, 2017, 3:04 AM
will kranz,
Jun 21, 2017, 5:08 AM