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Restoring a DEC PDP-11/05

wh3016

Experienced Member
Joined
Jul 20, 2022
Messages
50
Location
Massachusetts
Hello everyone, long-time lurker, first-time poster here

I have a DEC PDP-11/05 that came from the estate of an old-time computer guy. I'll admit I'm by no means an expert on minicomputer systems of this era, after all, this thing is pretty much twice as old as I am, but I saw a local listing for it and decided to pick it up. For the past 10 years, I've been collecting things like a few 68k macintoshes and an 8088 PC clone, but in 2019 I picked up three Teletype ASR-33's for free and spent some time getting them working. Since then I had been on the hunt for some 'big game' computer equipment, and after having a local PDP-8E (Maynard MA is right in my backyard) 'slip through my fingers' back in 2020, I was pretty excited to actually get my hands on a machine of this caliber.

The guy I bought the machine from said it powered up. I was a little nervous at first, because if one of the PSU components had gone bad, powering the thing up after 30 odd years very well could have let out the 'smoke. When I received the machine, it was pretty dusty, and had signs of a mouse living inside. Despite this though, it cleaned up pretty well. Visually, I see no signs of chewed wiring or corrosion. I should note that I pulled all the modules out before I began checking the power supply. None of the capacitors show any signs of leaking, and after probing the power connector, J2 on the underside, I am seeing the necessary +15V, -15V, and +5V, all within 5% of their values.

As for modules, the machine came with the following:

Slot 1- M9970
Slot 2-M7260, OP KD11B
Slot 3-M7261, OP KD11B
Slot 4- H214, OP MM11L
Slot 5- G116, OP MM11
Slot 6- G231, OP MM11

Slot 10- M792, OP DD11B
Slot 11- M7800, OP DD11B
Slot 14- M7892

Additionally, I have three other M7800 modules, two of which are still in their cardboard case and don't appear to have been used.

Now before I proceed, I wanted to ask you, folks, for advice on what to do next. Again I'm no expert on PDPs or unibus systems, but I'm eager to learn. I'm actually recent-grad electrical engineer, but I did take an assembly language course in college, which fueled my interest in machines where you can toggle data into the registers through switches.
 

bladamson

Veteran Member
Joined
Nov 11, 2018
Messages
915
Location
Appalachia
Oh wow, core memory huh? That is really cool. I'm not really qualified to help, but I'll be following this with interest. :D
 

MattisLind

Veteran Member
Joined
Sep 30, 2013
Messages
1,006
Location
Stockholm, Sweden
G116? Sounds strange. Should be G110 (or possibly G109)

There is one empty slot in the DD11B backplane, right. Your slot numbering look a bit weird to me. The DD11-B is four slots.

There need to be a G727 grant continuity jumper in there to have interrupts working properly. Or you can stuff in any other properly configured board.
Since I guess you don't have a TU60 tape drive (which was intended to connect to the M7892 board) you could use a TU58 emulator and connect it to a M7800 board. Configure the M7800 board for vector 300 / address 176500. The manual on the M7800 is quite detailed on how you jumper the board.

Unfortunately you have only 16kbyte memory so it won't be possible to boot RT11 on this machine unless you get more memory. You could get unibus memory. M7847 can be used in this machine for example. Or get another set of H214/G231/G110 boards.

You will be able to boot XXDP from the TU58 emulator on this machine. It even manages without interrupts working.

The M792 most likely contain the TU60 cassette bootstrap. You will need to toggle in the TU58 bootstrap by hand.

Another option is to try to get a TU60 drive. Then you can run CAPS-11 operating system on your system. But those cassettes are hard to find.

If the voltages are fine, fire it up with boards installed. Verify that you can do examine and deposit.

Good luck!
 

DarthRegister

New Member
Joined
Apr 14, 2016
Messages
2
According to http://www.bitsavers.org/pdf/dec/pdp11/rt11/v2c_Jan76/RT11v2C_SysRefJan1976.pdf RT-11 V2C will run in 8KW.
How usable that is, it doesn't say!

Warm feelings for this version of RT-11, as this was the first DEC operating system I used in my working life.
The documentation and flowcharts were very helpful implementing an RT-11 lookalike on Computer Automation LSI-2 with 64KB and double floppies.

V03 onwards got quite complex internally, and the simplicity got obscured.

Regards, Graham
 

Hunta

Experienced Member
Joined
Mar 23, 2021
Messages
188
Location
Samara, Russian Federation
Unfortunately you have only 16kbyte memory so it won't be possible to boot RT11 on this machine
But there are nuances :)
Code:
@DK7
RT-11SJ    V03B-00B

.D 56=5015

.TYPE V3USER.TXT
Welcome to RT-11 Version 3B. RT-11 V03B provides mainly new hardware
support and some minor enhancements over Version 3.

If you are using a terminal that requires fill characters,
modify location 56 with a Deposit command before proceeding with
system installation. LA36 DECwriter II and VT52 DECscope terminals
do NOT require such modification.


.D 56=0

.SHO
TT
RK  (Resident)
  RK7   = SY , DK
DL
DY
DS
DM
DP
DX
DT
MT
MM
RF
LP
BA


.SHO CONF

RT-11SJ    V03B-00B

Booted from RK7:
Resident Monitor base is 030464
USR is set SWAP
TT is set NOQUIET
Indirect file abort level is ERROR
Indirect file nesting depth is 3

LSI-11 Processor
Extended Instruction Set (EIS)
60 Cycle System Clock

No SYSGEN options enabled


.

Pay attention to the line -> Resident Monitor base is 030464
 

Hunta

Experienced Member
Joined
Mar 23, 2021
Messages
188
Location
Samara, Russian Federation
Code:
DDMNSJ.SYS    64  27-мар-79      DDMNFB.SYS    75  27-мар-79
PC    .SYS     2  27-мар-79      CR    .SYS     3  27-мар-79
CT    .SYS     5  27-мар-79      MTHD  .SYS     3  27-мар-79
MMHD  .SYS     4  27-мар-79      BA    .SYS     7  27-мар-79
ODT   .OBJ    10  27-мар-79      BATCH .SAV    26  27-мар-79
FILEX .SAV    18  27-мар-79      SRCCOM.SAV    11  27-мар-79
DUMP  .SAV     7  27-мар-79      TECO  .SAV    27  27-мар-79
README.TXT    36  27-мар-79      VT52  .TEC     5  27-мар-79
VEG   .TEC     4  27-мар-79      EDIT  .TEC     1  27-мар-79
INSERT.TEC     2  27-мар-79      LOCAL .TEC     2  27-мар-79
SORT  .TEC     3  27-мар-79      SYSMAC.MAC    36  27-мар-79
VTMAC .MAC     6  27-мар-79      VTHDLR.OBJ     8  27-мар-79
SYSF4 .OBJ    40  27-мар-79      GETSTR.FOR     2  27-мар-79
PUTSTR.FOR     2  27-мар-79      PLOT55.OBJ     3  27-мар-79
TEST55.FOR     5  27-мар-79      PAT   .SAV     7  27-мар-79
DEMOBG.MAC     2  27-мар-79      DEMOFG.MAC     3  27-мар-79
DEMOF1.FOR     2  27-мар-79      DEMOED.TXT     1  27-мар-79
DEMOSP.MAC    10  27-мар-79      DEMOX1.MAC     3  27-мар-79
 36 files, 445 blocks
 35 Free blocks
[2022-apr-21 11:34:02 info]  Files extracted from "RTV339.B" and written to "RTV339".
 

Roland Huisman

Veteran Member
Joined
Mar 24, 2011
Messages
1,396
Location
The Netherlands
Make your life easy... Get a unibone :biggrin:

Then you can emulate the maximum off memory and several devices like floppy and harddisks.
 

Roland Huisman

Veteran Member
Joined
Mar 24, 2011
Messages
1,396
Location
The Netherlands
Hi Hunta,

Sorry for the confusion... But i meant a UniBone for the topic starter... As I understand he has only the PDP11/05 and no further devices. Then a UniBone is really great. You can Emulate memory, M9312 bootstraploader, RK05, RL01, RL02, RX01, RX02 and what probably more that I don't know about...

You have nice qubus projects btw!

Regards, Roland
 

Hunta

Experienced Member
Joined
Mar 23, 2021
Messages
188
Location
Samara, Russian Federation
Hi, Roland!
Sorry for the confusion
It's OK :)
As I understand he has only the PDP11/05 and no further devices. Then a UniBone is really great.
I completely agree :)
You have nice qubus projects
Thanks :) But these are not finished projects, but rather - the study of FPGA and love for PDP-11. I'm currently having fun restoring XXDP sources (including early versions of DDP1-B001 and DDP2) :)

Regards, Serge
 

wh3016

Experienced Member
Joined
Jul 20, 2022
Messages
50
Location
Massachusetts
G116? Sounds strange. Should be G110 (or possibly G109)

There is one empty slot in the DD11B backplane, right. Your slot numbering look a bit weird to me. The DD11-B is four slots.

There need to be a G727 grant continuity jumper in there to have interrupts working properly. Or you can stuff in any other properly configured board.
Since I guess you don't have a TU60 tape drive (which was intended to connect to the M7892 board) you could use a TU58 emulator and connect it to a M7800 board. Configure the M7800 board for vector 300 / address 176500. The manual on the M7800 is quite detailed on how you jumper the board.

Unfortunately you have only 16kbyte memory so it won't be possible to boot RT11 on this machine unless you get more memory. You could get unibus memory. M7847 can be used in this machine for example. Or get another set of H214/G231/G110 boards.

You will be able to boot XXDP from the TU58 emulator on this machine. It even manages without interrupts working.

The M792 most likely contain the TU60 cassette bootstrap. You will need to toggle in the TU58 bootstrap by hand.

Another option is to try to get a TU60 drive. Then you can run CAPS-11 operating system on your system. But those cassettes are hard to find.

If the voltages are fine, fire it up with boards installed. Verify that you can do examine and deposit.

Good luck!
Glad to hear! I've seen several of your videos on youtube. A very neat channel you have there.

It's G110, not G116. You are correct. There are four M727 grant continuity jumpers installed. My mistake with the numbering, too- there are two DD11B backplanes installed in the chassis in addition to the 8-slot 'main' backplane. There are M920 'jumpers' installed between both DD11B's and the main backplane.

There are also two DEC M930C terminator modules that were included. One of which was seated in the leftmost slot (if you are looking towards the rear of the unit) Is there a numbering scheme that applies to the slots for Unibus?

As I mentioned previously, I had all of the modules pulled for power supply testing. Since all of the voltages appear to be within their appropriate ranges, I suppose I can begin re-populating the unit. For ease of testing, would there be a 'bare minimum' configuration based on the modules I have, just to verify that I can examine and deposit properly?

As far as connecting the machine to other devices for booting, I have the module with the Berg connector and cable that matches the connector on one of my ASR-33s. This leaves me under the impression that 4-20ma current loop signalling is employed. I do happen to have a current loop to RS-232 adaptor on hand as well.

I'll take a look and see what my options are for more memory. I initially didn't consider RT11, and was at least hoping to get some form of BASIC running.

From what I was told, this 11/05 (being the OEM model) was owned by Nabisco (presumably in use at their Smithfield, Rhode Island distribution facility) and was part of an early iteration of a barcode/inventory tracking system. The guy I bought it from had some paper tapes from Nabisco that went to a PDP-8/E that he sold.

PDP1105 internals empty.JPG
 

Dare

Experienced Member
Joined
Dec 28, 2015
Messages
75
Sounds like a fun system. I took a similar journey with my short-box 11/05. I was lucky in that the MM11-L memory system that came with my system (a G110, G231 and strangely, an H216) worked as-is. However I have since acquired an ME11-L (external memory chassis) and various additional MM11-L board sets that required extensive diagnostics and repair. If you have issues with your core memory, feel free to ask questions. I have some interesting repair experiences with these.

If you don't already have a console cable there are instructions on the web for how to make one (Interfacing with a PDP-11/05). It's pretty straightforward. Alternatively, I have built a console adapter based on a Teensy 3.1 that connects via USB and provides dynamic baud rate switching (PDP-11/05 Console USB Adapter). Otherwise with a simple console cable you're stuck at 2400 baud. Trivial to build, provided you can get a hold of a Teensy.

Be sure to inspect / clean all the Unibus slots before you try powering it up with boards in place. I found all sorts of junk wedged into the slots on my system.

Booting XXDP from a TU58 emulator hooked up to a second serial port is a great way to test the machine, provided the basics work. Some tests that I found helpful:
  • DZQKC / ZQKCF0.BIC / maindec-11-dzqkc-e-pb.bin - Comprehensive check of PDP-11/05 and PDP-11/20 instructions
  • MAINDEC-11-D1A / MAINDEC-11-D1AA-PB.ptap : Basic address test (up)
  • MAINDEC-11-D1DA-PB - BASIC MEMORY PATTERNS TEST
  • ZQMCG2.BIC - 0-124K WORD MEMORY (not ECC) TEST (my go-to test for validating proper memory functionality)
If you find that the system is not stable enough to run XXDP, you can perform various tests of basic system functionality directly from the console. You can actually run trivial programs directly out of the register file memory, making it possible to test rudimentary CPU operation without any memory in the system.

As others have said, a Unibone is a great addition to these systems, especially if you have no mass storage options. Although not strictly necessary, I also added a M9312 bootstrap module to my system, which provides a convenient console monitor on power-up (and saves wear and tear on the console switches).

Good luck with your system, and please post updates on your progress.
 

Hunta

Experienced Member
Joined
Mar 23, 2021
Messages
188
Location
Samara, Russian Federation
Code:
;
;        11/05 SEQUENCE TABLE
;
;        ORIGINATOR:    R. UBERTI
;        REVISION:    B    17-NOV-75
;
;
;
;    OPTION SWITCH        OPTION
;
;         0        MANDATORY TESTS.
;         8        POWER FAIL TEST.
;         9            ABOVE 4K MEMORY
;         10        KL11/DL11A TTY TESTS
;         11        UNIBUS TESTER (FACTORY ONLY).
;         12        SIZER.
;         13        DR11-C INTERFACE.
;         14        SYSTEM EXERCISERS.
;         15        DR11-A (BR INTERFACE).
;
;
;
;
;ACT    PROG    OPTION    RUN    PASS
;NO.    NAME    SWITCH    TIME    COUNT    COMMENTS
;
;******DIAGNOSTICS T1-T13 ARE RELEASED AS NON-CHAINABLE
;******PROGRAMS WITH NEW ACT SEQUENCE NUMBERS.  THEY HAVE
;******BEEN REMOVED FROM THE SEQUENCE TABLE.
;740    D0AA0    0    1    10    ;T1 - BRANCH TEST
;741    D0BA0    0    1    10    ;T2 - CON BRANCH TEST
;742    D0CA0    0    1    10    ;T3- UNARY TEST
;743    D0DA0    0    1    10    ;T4 - UNARY AND BINARY TEST
;744    D0EA0    0    1    10    ;T5 - ROTATE SHIFT TEST
;745    D0FA0    0    1    10    ;T6 - COMPARE TEST
;746    D0GA0    0    1    10    ;T7 - COMPARE NOT TEST
;747    D0HA0    0    1    10    ;T8 - MOVE TEST
;750    D0IA0    0    1    10    ;T9 - BIC AND BIT TEST
;751    D0JA0    0    1    10    ;T10 - ADD TEST
;752    D0KA0    0    1    10    ;T11 - SUBTRACT TEST
;753    D0LA0    0    1    10    ;T12 - JUMP TEST
;754    D0MA0    0    1    10    ;T13 - JSR, RTS, RTI TEST
164    D0NC0    0    1    10    ;T14
032    ZMMKB0    0    1    61    ;MEM:UP-DOWN ADDR TEST
024    ZMMDB0    0    2    2    ;MEM: BASIC TEST PATTERNS
025    ZMMEC0    0    15    5    ;MEM: MOVING 1'S AND 0'S
026    ZMMFB0    0    2    24    ;MEM: 1'S SUSCEPTIBILITY
113    ZQKCE0    0    2    2    ;11 FAMILY INSTR EXER.
027    ZMMGD0    0    2    30    ;MEM: WORSE CASE NOISE
031    ZMMIB0    0    3    20    ;MEM: RANDOM DATA
166    ZKWAB0    14    3    5    ;KW11L TEST
173    ZKLAD0    10    10    2    ;KL11/DL11A TTY TESTS
017    ZQKBE0    14    10    6    ;T17 4K SYS EXER.
256    ZSSAA0    12    10    1    ;SYSTEM SIZER
160    ZDRCD0    13    2    10    ;DR11-C TEST
170    D8LA1    15    2    10    ;DR11-A (BR INTERFCE)
151    ZKAQB0    8    4    10    ;POWER FAIL
143    D8AA0    11    2    10    ;UNIBUS TESTER (FACTORY ONLY)
036    ZQMBG0    9    2    15    ;MEMORY EXERCISER
;
;
;    END OF THE 11/05 SEQUENCE TABLE
;
 

wh3016

Experienced Member
Joined
Jul 20, 2022
Messages
50
Location
Massachusetts
I put all the modules back in their respective slots, but I'm not getting any activity on the front panel upon power-up. I know the panel is getting power and the LEDs are functional, as they all illuminate when all the backplane slots are empty. For reference, I tried toggling "Load address" and "Deposit" a few times, but no activity from the LEDs...
 

Roland Huisman

Veteran Member
Joined
Mar 24, 2011
Messages
1,396
Location
The Netherlands
Do you have the bus terminators installed? Empty spc slots also need a little board. Can you sent some pictures from your boards placed in the machine? In my opinion you have to go back to a basic minimal system and go from there.
 

gnupublic

Experienced Member
Joined
Jan 23, 2019
Messages
129
Location
Germany, Berlin
Hello,
nice machine! Is it possible you make a foto from the backplane(s). I think there are two inside? Are they connected with a M9401 or so? Im also missing any bus-resistor like M930. And the mentioned G727 mini card in the second backplane.
You may clean the contacts of the cards befor inserting them into the backplane.

It is most likley that the machine has some issures. Some month ago I got some 11/05 an all of them had problems.
You may start mit only the M7260 + M7261 card. Then you should be able (but only able) to "load address" what you key in the switch register. (With any deposit or examine you get an bus error and must reset the machine.)
If this works, you may add the core memory. Then you should be able deposit and examine something.
Next step would be connecting the serial interface and sending some characters.

Have fun and enjoy the machine!
Volker
 

gnupublic

Experienced Member
Joined
Jan 23, 2019
Messages
129
Location
Germany, Berlin
Hello,
nice machine! Is it possible you make a foto from the backplane(s). I think there are two inside? Are they connected with a M9401 or so? Im also missing any bus-resistor like M930. And the mentioned G727 mini card in the second backplane.
You may clean the contacts of the cards befor inserting them into the backplane.

It is most likley that the machine has some issures. Some month ago I got some 11/05 an all of them had problems.
You may start mit only the M7260 + M7261 card. Then you should be able (but only able) to "load address" what you key in the switch register. (With any deposit or examine you get an bus error and must reset the machine.)
If this works, you may add the core memory. Then you should be able deposit and examine something.
Next step would be connecting the serial interface and sending some characters.

Have fun and enjoy the machine!
Volker
Sorry, I have not seen your foto yet. So it looks ok. Terminators and bridges are there.
You may pull the bridge that connects the first with the second backplane. Put in the resistor in the last unibus slot of backplane 3. Then you may start with only M7260+ M7261...
 

wh3016

Experienced Member
Joined
Jul 20, 2022
Messages
50
Location
Massachusetts
Do you have the bus terminators installed? Empty spc slots also need a little board. Can you sent some pictures from your boards placed in the machine? In my opinion you have to go back to a basic minimal system and go from there.
There are two M930 terminators that were installed in the unit. One is visible on the upper left side of the picture, while the other is in the same row as the H214. I haven’t moved these since I received it.

The small boards in the lower left of the picture are M727 jumpers. They also haven’t moved.


Hello,
nice machine! Is it possible you make a foto from the backplane(s). I think there are two inside? Are they connected with a M9401 or so? Im also missing any bus-resistor like M930. And the mentioned G727 mini card in the second backplane.
You may clean the contacts of the cards befor inserting them into the backplane.

It is most likley that the machine has some issures. Some month ago I got some 11/05 an all of them had problems.
You may start mit only the M7260 + M7261 card. Then you should be able (but only able) to "load address" what you key in the switch register. (With any deposit or examine you get an bus error and must reset the machine.)
If this works, you may add the core memory. Then you should be able deposit and examine something.
Next step would be connecting the serial interface and sending some characters.

Have fun and enjoy the machine!
Volker
I’ll try removing everything but the M7261 and M7260 and see what happens.

I’ve attached a picture, hopefully it is clear enough.



Edit: I have pulled all modules but the two mentioned above. Still no LED activity when switches are toggled…
 

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