TOPS-20: Making more space in the public structure

The Panda distribution is for sure the easiest way to make contact with TOPS-20, and in a previous entry I explained how to set it up to run in a Raspberry Pi (or similar) computer. One of the challenges of using those ancient operating systems is the lack of support and/or documentation. Fortunately, there is a whole treasure of information in the internet, and a quite active newsgroup devoted to the PDP10 class computers, where some of the actual designers of those machines and those operating systems is happy to answer a beginners question about the work of their life.

On the other hand, one of the fun things one can do is to dig around and find the answers from himself!

The problem: lack of disk space in the public structure

The "public structure" is what in other environments we would call the "system disk" or the "root filesystem". The Panda Distribution comes with a public structure defined in a RP07 class disk. Those disks held about 476 Megabytes, and as far as I know the "regular" TOPS-20 did not support those devices for the public (boot) structure. The late Mark Crispin modified heavily the montitor (what we could call "kernel" nowadays) to support those big (at the time) disks. Just after the first boot, there is plenty of available space in Panda's TOPS20 structure:

@info disk

 TOPS20:<OPERATOR>

 3 Pages assigned

 500 Working pages, 500 Permanent pages allowed

 82831 Pages free on TOPS20:, 133545 pages used.

That is about 160 MBytes of space (remember that the PDP10 was a 36 bit machine, so our eight-bit bytes are not really the best unit in that environment). For a casual use it is obviously more than enough. But if you start installing stuff, testing things and messing around you can find yourself with a few thousands of pages left. In that case, you can do several things:

• Purge the old versions of the log files to free up space. Those files, called LOGFILE.LOG, accumulate themselves in the SYSTEM: directory (that is a logical which points to TOPS20:<SYSTEM> and can take a big chunk of space.
• Create another structure and mout it as a USER structure, using it to do your stuff.
• Add another volume to the TOPS20: structure. This is the best long-term solution and it will be explained in this blog entry.

Preparation

We must do two things before we start adding space: preparing a DUMPER tape and actually dumping (backing up) the TOPS20: structure.

Creating a bootable DUMPER tape.

The first thing we must do is to make a bootable TAPE which must contain the DUMPER utility. The DUMPER utility is the TOPS-20 backup program. Since we will create a new, pristine structure we need to be able to boot directly into DUMPER from tape to restore our current information.

The good news is that it is really easy to create a dumper tape:

• First, we will create a virtual tape, escaping to the KLH10 console (pressing CTRL-\) and typing:

@[HALTED: FE interrupt]

KLH10> devmount mta0 dumper.tap create

Mount requested: "dumper.tap"

KLH10> [mta0: Tape offline]

KLH10> cont

Continuing KN10 at loc 01063335...

@

• Now we have to copy the monitor program and DUMPER itself into the tape. We will use Mark Crispin's monitor, which supports big structures:

@copy system:monitr.exe mta0:

 <SYSTEM>MONITR.EXE.1 => MTA0:MONITR [OK]

@copy tops20:<subsys>dumper.exe mta0:

 <SUBSYS>DUMPER.EXE.1 => MTA0:DUMPER [OK]

@rewind mta0:

@unload mta0:

@

• And we are done. We just have to detach the virtual tape from the emulator, and keep the file safe

@[HALTED: FE interrupt]

KLH10> devunmount mta0

Unmount requested

[mta0: Tape offline]

KLH10> 

Backing up the system

Now we need to get a backup copy of our running system on tape. To do this we will shut down the system, and then we will use DUMPER to create the backup. These are the steps:

• Enable privileges and shut down the system typing CTRL-E followed by CEASE NOW

@enable

$^Ecease now

 TOPS20 Will be shut down IMMEDIATELY 

[Confirm]

12-Feb-2015 12:54:20 ACJ: System shutdown set by job 9, user OPERATOR, program C

EASE, TTY5

$

[Timesharing is over]

OPERATOR - Wait for the message "Shutdown complete" before

entering commands to PARSER.

[ni20_cmdchk: Illop=0 wd=4,,0 qe=1443101]

[dpni20-W: "tap0" multicast table ignored - interface not dedicated]

[ni20_cmdchk: Illop=0 wd=4,,0 qe=164061]

SJ  0: OPR>Killed Job 1, User OPERATOR, TTY13, at 12-Feb-2015 12:54:21

SJ  0:  Used 0:00:00 in 0:17:24

[dpni20-W: "tap0" multicast table ignored - interface not dedicated]

[ni20_cmdchk: Illop=0 wd=4,,0 qe=164061]

12-Feb-2015 12:54:24 HSYS: Shutdown complete

• Create a virtual tape to hold the backup. We do this as we did before, pressing CTRL-\ to access the console:

[HALTED: FE interrupt]

KLH10> devmount mta0 backup-tape.tap create

Mount requested: "backup-tape.tap"

[mta0: Tape online]

KLH10> cont

Continuing KN10 at loc 01003136...

$

• Run DUMPER and take the backup. This step can take some time. You must be careful to not forget to issue the CREATE command before the SAVE. The CREATE command allows you to do the full restore you'll need afterwards, adding to the backup tape the image of the directory structure.

$r dumper

[Using MTA-DUMPER:]

DUMPER>tape mta0:

DUMPER>create

DUMPER>save tops20:

 DUMPER tape #1, Thu 12-Feb-2015 1257. 

 TOPS20:<ALGOL>

 TOPS20:<BBOARD>

 TOPS20:<BLISS>

.

.

.

 TOPS20:<UNSUPPORTED>

 TOPS20:<UTF9>

 TOPS20:<UTILITIES>

 TOPS20:<WINDOW>

 Total files dumped:   7403

 Total pages dumped: 104812

 Directories dumped:    141

 CPU time, seconds:  570.00

• Detach the backup tape and shut down the simulator. Remember the system was already shut down, so we can quit KLH10 without damaging anything.

Now it is a good practice to make a copy of the virtual disk we are about to replace, just in case we are unable to restore the tape we have just made. Since we are going to create the disks from scratch, you can simply rename the file to avoid it to be overwritten. That is one of the nice things of emulation: we can do things we couldn't dream about if we were using real devices!

Creating the new system disks

Now we are going to create the new disk structure. The KLH10 distribution included in panda contains a configuration file which is appropriate to install a system from scratch. That file is inst-klt20.ini. We will modify this file to acomplish what we want to  do. The part of the file which contains the device definitions is:

devdef dte0 200   dte   master

devdef rh0  540   rh20

devdef rh1  544   rh20

devdef dsk0 rh0.0 rp    type=rp06 format=dbd9

devdef mta0 rh1.0 tm03  type=tu45

We will change the disk type to rp07 add another disk definition, so it will become:

devdef dte0 200   dte   master

devdef rh0  540   rh20

devdef rh1  544   rh20

devdef dsk0 rh0.0 rp    type=rp07 format=dbd9

devdef dsk1 rh0.1 rp    type=rp07 format=dbd9

devdef mta0 rh1.0 tm03  type=tu45

Now we will start the simulator. Be sure you have the mtboot.save file in the current directory and start kn10-kl using the modified configuration file:

$ ./kn10-kl inst-klt20.ini 

KLH10 V2.0H (MyKL) built Feb 12 2015 00:50:35

    Copyright ? 2002 Kenneth L. Harrenstien -- All Rights Reserved.

This program comes "AS IS" with ABSOLUTELY NO WARRANTY.

Compiled for LINUX on ARM with word model USEINT

Emulated config:

CPU: KL10-extend   SYS: T20   Pager: KL  APRID: 3600

Memory: 8192 pages of 512 words  (SHARED)

Time interval: SYNCH   Base: OSGET

Interval default: 60Hz

Internal clock: COUNT

Other: MCA25 JPC DEBUG PCCACHE EVHINT

Devices: DTE RH20 RPXX(DP) TM03(DP) NI20(DP)

[MEM: Allocating 8192 pages shared memory, clearing...done]

KLH10# ; Sample KLH10.INI for initial installation

.

.

.

KLH10# ; Load tape bootstrap directly

KLH10# load mtboot.sav

Using word format "c36"...

Loaded "mtboot.sav":

Format: DEC-CSAV

Data: 4067, Symwds: 0, Low: 040000, High: 054641, Startaddress: 040000

Entvec: JRST (120 ST: 0, 124 RE: 0, 137 VR: 0,,0)

KLH10# 

KLH10# ; Now ready to GO

KLH10# [EOF on inst-klt20.ini]

KLH10# 

Now we must attach the bootable dumper tape we build before, and start the virtual frontend:

KLH10# devmount mta0 dumper.tap

Mount requested: "dumper.tap"

[mta0: Tape online]

KLH10# go

Starting KN10 at loc 040000...

BOOT V11.0(315)

MTBOOT>

To load the monitor from the mounted tape, we will issue a '/L' command (without the quotes) and after that we will invoke the disk formatting procedure issuing a '/G143':

KLH10# go

Starting KN10 at loc 040000...

BOOT V11.0(315)

MTBOOT>/L

[BOOT: Loading] [OK]

MTBOOT>/G143

[For additional information type "?" to any of the following questions.]

Do you want to replace the file system on the system structure? 

The whole disk and structure formatting is as follows:

Do you want to replace the file system on the system structure? YES

Do you want to define the system structure? YES

How many packs are in this structure: 2

On which "CHANNEL,CONTROLLER,UNIT" is logical pack # 0 mounted? 0,-1,0

On which "CHANNEL,CONTROLLER,UNIT" is logical pack # 1 mounted? 0,-1,1

Do you want the default swapping space? Y

Do you want the default size front end file system? Y

Do you want the default size bootstrap area? Y

Do you want to enable password encryption for the system structure? Y

What is the name of this structure? TOPS20

[Structure "TOPS20" successfully defined]

[TOPS20 mounted]

?TOPS20 unit 0 has no BAT blocks.

Do you want to write a set of prototype BAT blocks? Y

?TOPS20 unit 1 has no BAT blocks.

Do you want to write a set of prototype BAT blocks? Y

PANDA PROGRAMMING, PANDA TOPS-20 Monitor 7.1(21733)-4 Internet: Loading host names

%%No SETSPD.

Be aware of the numbering of the controller (it is -1), and take almost all the defaults, excepting for the structure name, where you must specify TOPS20 explicitly. After that, our monitor will complain about not being able to load the internet address list and other stuff we don't need now. Eventually, the messages will stop. The next step will be to restore the backup we made previously.

Restoring our system

To begin the process we will press CTRL-C and will get a MX> prompt. Following from the last screen capture:

%%No SETSPD.

System restarting, wait...

Date and time is: Thursday, 12-February-2015 9:17PM

Why reload? 12-Feb-2015 21:17:48 ***BUGINF NOADDR*** Failed to find SYSTEM:INTERNET.ADDRESS file  Job: 0, User: OPERATOR

12-Feb-2015 21:17:48 ***BUGINF NOHSTN*** Failed to find host name file SYSTEM:HOSTS.TXT  Job: 0, User: OPERATOR

12-Feb-2015 21:17:48 ***BUGCHK NOACTF*** No account database - account validation disabled  Job: 0, User: OPERATOR

Why reload? OTHER - Question timeout

 DDMP: Started

No SYSJOB

12-Feb-2015 21:18:49 ***BUGCHK KNICFF*** PHYKNI - Cannot reload the NIA20  Job: 0, User: OPERATOR, Data: 600104

NO EXEC

MX>

Now we will load DUMPER into memory, following these steps:

MX>GET FILE mta0:

?

MX>GET FILE mta0:

MX>sTART

DUMPER>

Yes, the first command gives out and error, and the second one works. Notice you just have to type the first letter of the commands. A 'G' for GET FILE and an 'S' for START.

Now we must drop to the KLH10 console and mount the virtual tape which contains our backup:

DUMPER>[HALTED: FE interrupt]

KLH10> devmount mta0 backup-tape.tap 

Mount requested: "backup-tape.tap"

[mta0: Tape online]

KLH10> c

Continuing KN10 at loc 01053253...

DUMPER>

We are almost there. To restore the contents of the tape we will use the CREATE and RESTORE commands. Again, do not forget to issue the CREATE before the RESTORE. Ignore the error messages and be ready to wait for a while.

DUMPER>TAPE MTA0:

DUMPER>CREATE

DUMPER>RESTORE TOPS20: TOPS20:

UNNAMED saveset 12-Feb-2015 2057

%Failed to create TOPS20:<ROOT-DIRECTORY>Cannot find error message file - RETRYING

12-Feb-2015 21:24:52 ***BUGINF RTCRAT*** JSYSF: ROOT-DIRECTORY CRDIR attempted  Job: 1, User: OPERATOR, Data: 777576170026, 60000000

0000

12-Feb-2015 21:24:52 ***BUGINF RTCRAT*** JSYSF: ROOT-DIRECTORY CRDIR attempted  Job: 1, User: OPERATOR, Data: 777576170026, 60000000

0000

?Directory TOPS20:<ROOT-DIRECTORY> not created - Cannot find error message file

TOPS20:<ACCOUNTS> created

TOPS20:<ALGOL> created

TOPS20:<BBOARD> created

TOPS20:<BLISS> created

TOPS20:<BLISS-SOURCES> created

TOPS20:<CHIVES> created

TOPS20:<CHIVES.V1> created

TOPS20:<CHIVES.V1.CONFIG> created

TOPS20:<CHIVES.V1.DOCUMENTATION> created

TOPS20:<CHIVES.V1.SOURCE> created

TOPS20:<CLISP> created

TOPS20:<DECNET-SOURCES> created

.

.

.

TOPS20:<UTILITIES> created

TOPS20:<WINDOW> created

 Loading files into TOPS20:<ALGOL>

 Loading files into TOPS20:<BBOARD>

 Loading files into TOPS20:<BLISS>

.

.

.

Loading files into TOPS20:<TSU>

 Loading files into TOPS20:<UNSUPPORTED>

 Loading files into TOPS20:<UTF9>

 Loading files into TOPS20:<UTILITIES>

 Loading files into TOPS20:<WINDOW>

 End of Tape.

 Total files restored:   7402

 Total pages restored: 104811

 Directories created:   140

 Files skipped:     1

DUMPER>

And we are almost done! Now we just go back to the KLH10 console and quit the simulator. If we check the working directory we'll found two disk images (and possibily the old, renamed image). Now we have to modify the working configuration to add the newly created disk (the original name is klt20.ini) and start the simulator. If everthing has been done properly, we will be able to enjoy our new, super-sized public structure!

@info disk

 TOPS20:<OPERATOR>

 3 Pages assigned

 500 Working pages, 500 Permanent pages allowed

 297809 Pages free on TOPS20:, 134943 pages used.

Remember you can get the panda distribution, which includes both the PANDA TOPS-20 image and the KLH10 emulator (compiled for x86 linux) here. Enjoy!

Ten over Pi

In a previous post I did a small incursion into the business oriented data processing. The system I used to illustrate an example of a CODASYL database was a simulated PDP-10 running the TOPS-10 operating system hosted in a Raspberry Pi computer.

TOPS-10 was quite a nice operating system for its time. It has some "modern" capabilities associated to mainframe-class computing, including a somehow advanced accounting system, job protection, resource allocation based on user and group, priority based scheduling, operator interface and batch system. Its command language is, anyway, quite basic and its help system is limited.

The successor to TOPS-10 for the PDP-10 architecture was named, in a show of originality, TOPS-20. It was itself based on a previous operating system developed by a private company named TENEX. TOPS-20 supported the execution of TOPS-10 binaries, but was an enormous improvement over its predecessors...And we could say it was also a big improvement over its successors too. Its command processor has an awesome feature, similar to the command completion we find in "modern" shells as bash or ksh. The difference is that the TOPS-20 command processor "knows" about the syntax and options of whatever you are typing and offers you a choice of suitable completions. And that facility can be used from user programs too... Incidentally, those of you who are openVMS users or hobbyists can experience that kind of help in the MULTINET command. Press '?' and you will get a list of options. Press 'ESC' and your current typing will be completed, as long as there are just one possible completion.

In this post we will see how we can set up a simulated TOPS-20 system. And, specifically, we will set it up on a Raspberry Pi computer. So we will have a mainframe class computer within a credit-card sized gizmo...

Simulating a KL10 system

Our good friend simh is not a good option to run TOPS-20. The reason is simh emulates a Decsystem-10, based on the KS-10 CPU. The KS-10 was a scaled down version of the "big" PDP-10 machines. It is posible to run TOPS-20 in a KS-10, but it is limited to the 4.something version. The last TOPS-20 version, the one we will want to run, is 7.1. Nevertheless, the real reason we will not want to use simh is the lack of the NI20 networking interface, necessary to plug the simulated machine into the network, either internet, decnet or both. Fortunately, there is another simulator we can use: Ken Harrenstien's KLH10. 

KLH10 has not been enhanced for some time. The newest version you can get, as far as I know, comes with a full image of TOPS-20, ready to be used. This is the work of Mark Crispin, and can be found also here. Unfortunately, the package contains binaries just for Linux over intel processors. Since we want to use a Raspberry, which is ARM-based, we will have to compile KLH from sources. 

The directory structure we get after expaning the tarball is:

panda-dist -- klh10-2.0h --- doc

                         +-- contrib

                         +-- run

                         +-- src

                         +-- bld  --- fbppc

                                  +-- fbx86

                                  +-- lnx86

                                  +-- lnxarm

                                  +-- lnxppc

                                  +-- nbaxp

                                  +-- nbx86

                                  +-- osfaxp

                                  +-- solsparc

We must start the compilation from the appropiate bld subdirectory. For the pi we could use the lnxarm one, but in my experience the setup in that directory does not work very well. What I did was to create another subdirectory (which I called lnxarmpi) and to copy everything from lnx86. Then, open the Makefile in your editor of choice and edit the stanza:

CENVFLAGS = -DCENV_CPU_I386=1 -DCENV_SYS_LINUX=1 \
               -DKLH10_DEV_LITES=1 \
               -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE 

So it reads:

CENVFLAGS = -DCENV_CPU_ARM=1 -DCENV_SYS_LINUX=1 \
            -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE 

That is, change CENV_CPU_I386 to CENV_CPU_ARM and remove the KLJ10_DEV_LITES definition (there is no parallel port in the Pi).

Before trying to compile KLH10 we must do another change. Move to the src directory and search for the base-kl rule. You can now create a new rule with a different name or simply edit the current one, changing these lines:

     -DKLH10_ITIME_INTRP=1   \
     -DKLH10_CTYIO_INT=1     \

To:

     -DKLH10_ITIME_SYNC=1   \
     -DKLH10_CTYIO_INT=0    \ 

This magic spell comes from this alt.sys.pdp10 post.The reason is "high performance" computers wreck the asynchronous mechanisms of KLH10. Of course, KLH10 was written during the late 90's so almost every current computer is a "high performance" platform. Even the humble Rapsberry Pi. Oh, and aparently there is no fix for that problem (I guess the whole simulator would have to be reengineered). I tried changing some timer related constants, just as a wild try, and did not succeed.

Once you have done this, change to the bld/lnxarmpi directory and issue the "make base-kl" command (unless you created a new rule; in that case use that new rule name). And then go for a coffee. Or two. The Raspberry Pi is not a fast machine!

Once the compilation is over, just follow the instructions you will find in the panda distribution package to do the initial run and setup of TOPS-20. If everything goes well you will have a telnet-accessible TOPS-20 system, connected to the internet (or, at least, to your local network). The system has a bunch of goodies: FORTRAN, COBOL, PASCAL and other compilers. Several games (text based, of course), including the original ADVENTURE (type "run advent" to play), colosal cave, a VT version of STARTREK and some more.

To learn about the system itself, nothing better than the original user manual. You can find a webified copy at http://tilt.twenex.org/ The original manuals are also available in scanned format at http://bitsavers.trailing-edge.com/pdf/dec/pdp10/TOPS20/. If you want to get deeper into TOPS-20 you will need at least the administration manuals.

Finishing touch

Having an internet connected TOPS-20 emulated system is cool, but it is even cooler to enable the "native" networking of those machines: DECNET. To do it just add the following lines at the end of the SYSTEM:7-1-CONFIG.CMD file:

DECNET MAXIMUM-ADDRESS 1023

NODE NODNAM A.NNNN

DECNET ROUTER-ENDNODE

ETHERNET 0 DECNET

Use your own nodename instead of NODNAM and your area and address instead of A.NNNN. Reboot your system and DECNET should come up. Remember to set up adequately the network interface (check the KLH10 documentation about setting up a DECNET capable configuration). Now, to populate your DECNET databases, you must use the SETNOD program:

@RUN SETNOD

SETNOD> SET NODE N.MMM NAME NODE1

SETNOD> SET NODE X.YYYY NAME NODE2

(...)

SETNOD>SAVE FILENAME

SETNOD>INSERT

The SAVE command saves the entered nodes into a binary file. The INSERT command updates the live tables with the defined nodes (something similar to the SET KNOWN NODES ALL command in VMS NCP). To reload the node database at startup, add the following lines to SYSTEM:7-1-SYSJOB.RUN, just after the ^ESET LOGIN ANY:

RUN SYS:SETNOD

GET FILENAME

INSERT

EXIT

Replace FILENAME by the name you used when you saved the node database from SETNOD.

You must also uncomment three lines from the file SYSTEM:SYSTEM:CMD


WAIT 5
NCP SET CIRCUIT NI-0-0 SERVICE ENABLED
NCP SET CIRCUIT NI-0-0 STATE ON       

And this is all for now. As always, if you want to try any of these recipes and have any kind of trouble, just drop a commend and I will try to help..

Post-scriptum.

This post has been in draft status for a while. I begun to wrote it just after the one about TOPS-10. When I was about to publish it, Mr. Mark Crispin, the man behind the PANDA distribution and a lot of other things, passed away. I did not have the pleasure to know him, neither personally nor thru electronic communication, but I have read his comments in the PDP-10 mailing lists and other places. It would be presumptuous to pretend to pay him an homage in this humble blog post, so all what I will say is a very big THANK YOU. We human beings all pass away, but for some admirable people, their work will live forever.

Update

I have just run into this post: http://victor.se/bjorn/its/raspi.php, which explains clearly and succintly the steps to do to run KLH10 in the Raspberry Pi, including a patch for KLH which makes it much easier to network. To apply the tap patch, just download it into the main panda distribution unzip directory and run:

$ patch -p0 < tuntap.patch

And then rebuild KLH10.