Boot settings for RSX-11

[Paulo Rebordão]

Where can I find the file (and its name) that executes commands and assignments when RSX starts? Similar to the boot.ini for Simh

I created a new device and want to load it automatically at startup.

[Mark Matlock]

Paulo,

  The first command file that is executed by a RSX boot up is LB:[1,2]STARTUP.CMD 

  At the end of it you will find that a second command file that contains user specific startup commands. This maybe called invoked either by a @ or by a  .CHAIN command. The @ acts like a subroutine call and returns back to the STARTUP.CMD afterward and the .CHAIN jumps into the new command file and does not return.

  The RSX distributed by Johnny uses LB:[1,2]USERPROG.CMD as the user startup file and the original PiDP-11/70 RSX used LB:[1,2]INSPROG.CMD as the user startup file.

  When added new things, it is often best to put them at the end of these command files so that an error does not disrupt normal RSX startup and secondly your user commands may need some service that has to be started first (e.g. DECnet, TCP/IP or an RPM package).

Best,

Mark

On Apr 7, 2026, at 11:47 AM, Paulo Rebordão <pjreb...@gmail.com> wrote:

Where can I find the file (and its name) that executes commands and assignments when RSX starts? Similar to the boot.ini for Simh

I created a new device and want to load it automatically at startup.

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[Paulo Rebordão]

I logged as System and I'm looking at [1,2]INSPROG.CMD but can't change it. Permissions ?

Paulo Rebordão

[Mark Matlock]

Paulo,

   It is likely a permission issue. Try this:

>SET /UIC=[1,2]

>EDT LB:[1,2]INSPROG.CMD

At this point you would be in EDT and should be able to edit the INSPROG.CMD file.

The topic of file protection is explained in RSX: A User’s Guide on page 90. You can find a copy of that book in .pdf format at:

https://www.bitsavers.org/pdf/dec/pdp11/rsx11m_s/Pieper_RSX_A_Guide_For_Users_1987.pdf

Also p. 14 covers Privilege and Identification based on UIC.

Best,

Mark

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[Paulo Rebordão]

It's not working. Attempting to change the file inside Emacs gives "read only buffer"

Paulo Rebordão

[Mark Matlock]

Paulo,

   That is the error you would get with EMA, Johnny’s Emacs like editor, if you don’t have the privilege to edit the file.

DSP LB:[1,2]INSPROG.CMD

Will show all the file’s characteristics including the file owner and protection. The SYSTEM file protection should be RWED so you need to have your UIC set to [1,2] or other system UIC [group,user] where group is 10 or less. Are you set to DCL? Do you have a $ prompt or a > prompt ? If DCL then change your UIC protection with

SET UIC [1,2]

PWD should show your current directory and your UIC protection, for example:

$ PWD

DU0:[MATLOCK]  Named  TT25:

Protection UIC:  [1,2]

Best,

Mark 

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[Johnny Billquist]

On 2026-04-07 20:05, Mark Matlock wrote:
> Paulo,
>
>   The first command file that is executed by a RSX boot up is LB:
> [1,2]STARTUP.CMD

Right.
However, also be aware that you can actually modify the booted system
image, using VMR. Which means you don't need to stuff things into
STARTUP.CMD if you don't want to.

>   At the end of it you will find that a second command file that
> contains user specific startup commands. This maybe called invoked
> either by a @ or by a  .CHAIN command. The @ acts like a subroutine call
> and returns back to the STARTUP.CMD afterward and the .CHAIN jumps into
> the new command file and does not return.

That obviously depends on what image you are using. In a standard RSX
system, there is nothing more than STARTUP.CMD. Mark's image have that
chaining at the end. I did a call to USERPROG.CMD where people can
customize things that will be untouched if things get updated. Others
might have done other things...

>   When added new things, it is often best to put them at the end of
> these command files so that an error does not disrupt normal RSX startup
> and secondly your user commands may need some service that has to be
> started first (e.g. DECnet, TCP/IP or an RPM package).

Well. If things go wrong, it needs fixing anyway, so it don't really
matter *that* much where you place it.
Note that my image actually logs the console terminal out at the end of
STARTUP.CMD. If you place anything after that, it won't be run at all.

Johnny

--
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

[Johnny Billquist]

Emacs will set the buffer read-only if the file protection suggest it's
a file with just read permissions. However, if you are running with a
system uic, then you can write a new version of the file anyway. To
toggle the read-only attribute of a buffer, just hit ^X ^Q

If you do that, and you are not actually allowed to write the file,
you'll get an error when you try saving. So no real danger in this.

Toggling the read-only attribute can sometimes also be nice in the other
direction. If you open a file, but don't want to modify it...

Johnny

On 2026-04-08 00:53, Paulo Rebordão wrote:
> It's not working. Attempting to change the file inside Emacs gives "read
> only buffer"
>
> Paulo Rebordão
>
>
>
> On Tue, Apr 7, 2026 at 10:08 PM Mark Matlock <ma...@rsx11m.com
> <mailto:ma...@rsx11m.com>> wrote:
>
> Paulo,
>    It is likely a permission issue. Try this:
>
> >SET /UIC=[1,2]
> >EDT LB:[1,2]INSPROG.CMD
>
> At this point you would be in EDT and should be able to edit the
> INSPROG.CMD file.
>
> The topic of file protection is explained in RSX: A User’s Guide on
> page 90. You can find a copy of that book in .pdf format at:
>
> https://www.bitsavers.org/pdf/dec/pdp11/rsx11m_s/

> Pieper_RSX_A_Guide_For_Users_1987.pdf <https://www.bitsavers.org/
> pdf/dec/pdp11/rsx11m_s/Pieper_RSX_A_Guide_For_Users_1987.pdf>

>
> Also p. 14 covers Privilege and Identification based on UIC.
>
> Best,
> Mark
>
>
>> On Apr 7, 2026, at 2:47 PM, Paulo Rebordão <pjreb...@gmail.com

>>> <pjreb...@gmail.com <mailto:pjreb...@gmail.com>> wrote:
>>>
>>> Where can I find the file (and its name) that executes
>>> commands and assignments when RSX starts? Similar to the
>>> boot.ini for Simh
>>>
>>> I created a new device and want to load it automatically at
>>> startup.
>>>
>>>
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[Johnny Billquist]

On 2026-04-08 01:23, Mark Matlock wrote:
> Paulo,
>    That is the error you would get with EMA, Johnny’s Emacs like
> editor, if you don’t have the privilege to edit the file.

Sortof. If you have a file with [R,R,R,R] the buffer will be marked
read-only even if you have a system uic. But you can toggle the
read-only status of a buffer easily enough. And if you actually have the
rights to write a new version of the file, then all will work fine when
you try saving, or else you'll get an error then about that.

> Will show all the file’s characteristics including the file owner and
> protection. The SYSTEM file protection should be RWED so you need to
> have your UIC set to [1,2] or other system UIC [group,user] where group
> is 10 or less. Are you set to DCL? Do you have a $ prompt or a >
> prompt ? If DCL then change your UIC protection with
>
> SET UIC [1,2]
>
> PWD should show your current directory and your UIC protection, for example:
>
> $ PWD
> DU0:[MATLOCK]  Named  TT25:
> Protection UIC:  [1,2]

I don't think PWD is a DCL command. You have some modified stuff around? ;-)
The DCL command is SHOW DEFAULT

Johnny

[Paulo Rebordão]

I had a look at Pieper's book and learned how to see and change permissions and it worked for me. 

I updated INSPROG.CMD, adding my 3 additional lines at the end just before the boot complete message. 

Paulo Rebordão

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