TOPS-10 REACT Documentation

[Jeremy Doolin]

I've recently decided to dabble with TOPS-10 and some MACRO-10 assembly. I'm able to get logged in with pre-configured users, but I'd like to create a new one for myself. Based on the documentation I've found, I need to use a tool called REACT, which has a help page, but that is less than detailed in its documentation. 

I've looked through several DEC manuals trying to find more, but to not avail, unless i've missed something. Can anyone point me to the right manual, or any other detailed documentation? 

Jeremy Doolin

[Eric Swenson]

From an email sent Rich Alderson some time ago:

You need to run the REACT program to set up new users. This requires 1,2
privileges, so it's lucky that the console job is there. There is no manual
online for REACT; typing a question mark "?" at a prompt will give you some
information about what is expected at that point.

Short tutorial:

.r react

REACT>insert [12,12]
New user name: anders
USER>password somestringorother
USER>personal "Anders Jensen"
USER>require
REQUIREMENTS>no change
REQUIREMENTS>done
USER>done

User ANDERS (PPN [12,12]) created with password SOMESTRINGOROTHER

REACT>exit

That may look a little different on a system version earlier than 7.04. Let us
know if you have questions.

On Sep 19, 2025, at 13:14, Jeremy Doolin <jdo...@gmail.com> wrote:



I've recently decided to dabble with TOPS-10 and some MACRO-10 assembly. I'm able to get logged in with pre-configured users, but I'd like to create a new one for myself. Based on the documentation I've found, I need to use a tool called REACT, which has a help page, but that is less than detailed in its documentation. 

I've looked through several DEC manuals trying to find more, but to not avail, unless i've missed something. Can anyone point me to the right manual, or any other detailed documentation? 

Jeremy Doolin

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[Eric Swenson]

REACT is documented in this manual:

http://www.bitsavers.org/pdf/dec/pdp10/TOPS10_softwareNotebooks/vol15/AA-P512C-TB_TOPS-10_Software_Installation_Guide_Oct88.pdf

[steve...@gmail.com]

There's also an example of REACT use on Quentin's Blog FAQs:

https://www.quentin.org.uk/tops-10-faq/

[Jeremy Doolin]

Thanks everyone, this is exactly what I was looking for.  However, it would appear that I'm using the version 6 TOPS-10 that comes with the PiDP-10 distribution, and the version of REACT in every one of those examples is for version 7. 

Are there any procedures for installing version 7? 

[Ric Werme]

Ultimately, REACT stuff is small stuff.  I had managed to completely forget about the program, but then again, I wasn't the one create accounts at CMU or DEC.

On the PiDP-10 I mostly gave my account most of the privileges offered.  I knew I wanted the permission to use I/O instructions and whatnot.

My bigger question was my DEC account [10, 407] or [10,417]?  And even that doesn't really matter.

Keep in mind your goal is to write some assembler code.

As for V7, are you talking about REACT or TOPS-10?  V6 was the last release that ran on KA10s. later releases were too focused on paging issues, and the KA doesn't have page tables.  And you have little need to worry about them.

[Ric Werme]

"This requires 1,2 privileges, so it's lucky that the console job is there."

The [1,2] password is FAILSA.  (Lower case works.)

[steve...@gmail.com]

"Thanks everyone, this is exactly what I was looking for.  However, it would appear that I'm using the version 6 TOPS-10 that comes with the PiDP-10 distribution, and the version of REACT in every one of those examples is for version 7. 

Are there any procedures for installing version 7?"

I got my initial copy of TOPS-10 7.03 from Quentin's Blog:

https://www.quentin.org.uk/2018/02/15/configuring-pdp10-tops-10-for-online-use/

He refers to "If you are using the pre-configured Tops-10 disk packs then you don’t need to do the MONGEN" with a hot link to those disk images.

You can either:

1) Replace the disk images in the TOPS-10 folder in, I think, /opt/pidp10/systems/tops10. If the disk image file names are the same as for version 6.03 then you are fine. Otherwise, You'll need to edit the /opt/pidp10/systems/tops10/boot.pidp file to make it attach to these new disk images instead

2) Create an entirely new directory for TOPS-10 7.03 in the /opt/pidp10/systems folder, copy the TOPS-10 v7.03 disks into it, and using /opt/pidp10/systems/tops10/boot.pidp as a model recreate it for TOPS-10 7.03. Once this is done, you'll need to edit the /opt/pidp10/systems/selections (?I'm not exactly sure that's the file name, but something like that) and add an option for your new TOPS-10. It's fairly clear how a new option is added. Also, see page 9 of the PiDP-10 Systems User's Guide for info on the front panel switches when booting.

WARNING, If I recall correctly, TOPS-10 7.03 does not run on a KA-10 CPU. It needs a KS-10 CPU. As I recall, I had to edit the pdpcontrol.sh file so that it allowed using a KS-10 CPU. All of the front panel lights and switches still work with a PiDP-10 KS-10 CPU even though a real KS-10 does not have a front panel on it. Let me know if you need more details on this, e.g., I can send you my modified pdpcontrol.sh file if you don't know how to do that yourself.

-- steve

[Jeremy Doolin]

I replied earlier, but I think I accidentally replied to a single author. Oops. Anyway, thanks to everyone here I'm off and running. 

I got the TOPS-10 7.03 distribution and created a new system option for it on the PiDP10. Then modified pdpcontrol.sh so that it would start a KS-10 emulator. I did have to write a custom boot.pi{dp}, as the disks were different. Everything works, and the version of REACT behaves exactly as the examples provided in this thread. 

I've been happily working my way through Michael Singer's "Introduction to DECSystem-10 Assembler" all evening. TECO is surprisingly usable, though I miss EMACS from ITS. 

Thanks everyone. It's pretty cool getting tips from people who actually worked with these systems 

[Ric Werme]

I hadn't seen Singer's book before, it would have been very handy to me nine years before he wrote it.  :-)

It looks pretty good.  A few comments:

Use PUSHJ/POPJ for subroutine calling.  Pass arguments in registers.

Define registers T1-T4 for various temporary tasks including arguments to subroutines and define P1-P4 for "permanent" data that subroutines must not change (they can save and restore them with PUSH/POP).

You've seen the MAKE and  TECO commands.  Try "MAKE LOVE".