PiDP11

[Gary Robertson]

Dear all,

I am reasonably new to the PiDP11 system. I currently have two units configured, one with the Oscar front end and the other as a blind unit. Spending time mainly using RSX11M Plus at present.

Can someone please tell me if there is an easy way to change the DECnet configuration to allow these two units to co-exist on the same network and be 'aware of each other'. I started a SYSGEN operation on one but ended up aborting it as I haven't performed a SYSGEN since early 90's. 

How can I change the system name from RSX11M?

What is the significance of the FRODO node that is defined in boot up? I can TELNET FRODO but cannot SETHOST FRODO. Exact opposite for RSX11M.

Please forgive ignorance.

As a note, superb system, I never thought I would enjoy a PiDP11 as much as I do..

Thanks in advance..

[Johnny Billquist]

Please change to use the RSX distribution I created.
There are many reasons to do that, and one of them is that you'll get
into a configuration dialog at first boot where you can select the node
number and name you want, which will solve your immediate question/problem.

Johnny

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Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: b...@softjar.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol

[Gary Robertson]

Johnny,

Thank you for your reply.

As  I am new to the forum, can you please tell me where I can find the RSX distribution you refer to?

Thanks again, much appreciated.

[Johnny Billquist]

Gary, start with http://mim.softjar.se/pidp.htm for information about
the image, where to download it, and how to use it.

In there, you then also have links to RPM, which allows you to install
some other software onto your RSX system, and get up and running.

And feel free to ask any questions that pop up. Happy to help.

Johnny

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[Mark Matlock]

Gary,

    Welcome to the PiDP-11/70 and RSX11M ! Also, I totally agree that you should take a look at Johnny’s RSX11M+ distribution.

    Also, here are are specific answers to your questions.

On Feb 3, 2026, at 1:38 AM, Gary Robertson <gary.rob...@gmail.com> wrote:

Dear all,

I am reasonably new to the PiDP11 system. I currently have two units configured, one with the Oscar front end and the other as a blind unit. Spending time mainly using RSX11M Plus at present.

Can someone please tell me if there is an easy way to change the DECnet configuration to allow these two units to co-exist on the same network and be 'aware of each other'. I started a SYSGEN operation on one but ended up aborting it as I haven't performed a SYSGEN since early 90's. 

   To change a Node Name and DECnet address in RSX11M+ is quite simple. You need to edit the file LB:[5,54]CETAB.MAC using an editor CFE that uses NCP style commands and makes the changes for you. As I believe a good example is worth 1,000 pages of reference manuals, below is an example of changing NODE name Frodo to BILBO and the DECnet address from 30.1 to 30.300 Note that when you exit CFE all you have really done is created a new version of LB:[5,54]CETAB.MAC During the next boot-up DECnet will use this updated info. If you make a mistake, simply delete the newly created CETAB.MAC and the previous version will be used.

>SET /DEF=LB:[5,54]

>INS CFEFSL

I>CFE

Enter filename: cetab

CFE>SHOW EXE CHAR

Executor characteristics as of 3-FEB-2026 08:11:14

  Identification = Frodo M100-04 RSX11M+ V4.6

  Name = FRODO , Address = 30.1, Host = 30.1 (FRODO ),

  Confidence timer = 30

  Incoming proxy = Enabled

  Outgoing proxy = Enabled

  Segment buffer size = 576

  Delay factor = 32, Delay weight = 2

  Incoming timer = 15, Outgoing timer = 30

  Inactivity timer = 30, Retransmit factor = 5

  Maximum links = 10,  Maximum node counters = 32

  Type = Area, Verification state = On, Maximum address = 1023

  Maximum cost = 1022, Maximum hops = 10

  Routing timer = 300, Maximum broadcast endnodes = 32

  Broadcast routing timer = 40

  Maximum area = 63, Area maximum hops = 10

  Area maximum cost = 1022

CFE>DEF EXE NAME BILBO

CFE>DEF EXE HOST 30.300

CFE>EXIT

>DIR CETAB.MAC

Directory DU0:[5,54]

3-FEB-2026 08:13

CETAB.MAC;54        6.         03-FEB-2026 08:11

Total of 6./6. blocks in 1. file

How can I change the system name from RSX11M?

See above, but also in RSX11M+ there is a command that can change the system name:

>CON SET SYS NAME=BILBO

This is conveniently done in the LB:[1,2]STARTUP.CMD file where the CON ONLINE ALL command is located. Note that later in boot-up the system name in

DECnet’s CETAB.MAC will override the previous name. 

 

What is the significance of the FRODO node that is defined in boot up?

In the book “Where Wizards Stay Up Late” that describes the development of the ARPAnet and ultimately the internet, Email became one of the “killer apps” but node naming became a problem because (p. 252) “Every host machine had a given name, and everyone wanted to be named Frodo."

I can TELNET FRODO but cannot SETHOST FRODO. Exact opposite for RSX11M.

Telnet uses TCP/IP and nodes and their IP addresses must be defined in LB:[1,2]HOSTS.TXT unless your local DNS is doing it.

SET HOST activates RMT which uses DECnet addresses that are either defined in CETAB.MAC using CFE or is defined in LB:[5,54]NNS.DAT using the NNCFSL which can collect node names from other DECnet nodes from its menu based commands.

Note that if you want to freely transfer files between DECnet nodes with NFT, PROXY ACCESS needs to be activated in CETAB.MAC by CFE and the LB:[5,54]PROXY utility is used to define various PROXY connections so that account and password info does not have to be specified in NFT DECnet file transfer commands.

Please forgive ignorance.

As a note, superb system, I never thought I would enjoy a PiDP11 as much as I do..

Please note! Johnny Billquist’s earlier post on using his PiDP-11/70 distribution is something I also recommend. It can be found at:

http://mim.softjar.se/pidp.htm

The “Frodo” RSX11M+ disk image that was distributed with the PiDP-11/70 was an attempt at the time, to give users a working RSX1M+ system with layered software preinstalled to provide an immediately useful system. It is now quite dated and Johnny’s TCP/IP and RPM systems now provide a more easily configurable and much more up to date experience because it has a huge number of updates to both RSX and the layered DEC software as well as DECUS products.

Best,

Mark Matlock

[Gary Robertson]

Thank you all for your assistance, much appreciated. I will digest your posts and do as you suggest.

Thanks again..