memory map for RT-11 v 5

Jerome H. Fine jhfinedp3k at
Tue Jul 26 22:31:16 CDT 2016

I forgot to remove the "Spam Key" notice that my ISP puts into most of
my e-mail when I replied the first time - I apologize!!!

 >On Sunday, July 24th, 2016 at 14::29:59 -0700, Don North wrote:

> >On 7/24/2016 8:06 AM, william degnan wrote:
>> >On Jul 24, 2016 8:58 AM, "Jerome H. Fine" <jhfinedp3k at> 
>> wrote:
>>>> On Wednesday, July 20th, 2016 at 18:02:44 - 0400, william degnan 
>>>> wrote:
>>>> Is there a minimum memory requirement for RT-11 v5?  I was 
>>>> discussing with
>>>> Ray Fantini about it today, unsure...anyone know if 16K will work 
>>>> (from
>>>> 000000).
>>>> Bill
>>> You need to be more specific!  Starting with V05.00 of RT-11 in 1983,
>>> there were a total of 17 versions released up to V05.07 in 1998, 
>>> including
>>> sub-versions V05.01B, V05.01C, and V05.04A to V05.04G of RT-11.
>>> Up until V05.05 of RT-11, RT11SJ.SYS required the least memory which
>>> was replaced with RT11SB.SYS for V05.06 and V05.07 of RT-11.
>>> Attempts to boot from RT11SJ.SYS under V05.00 of RT-11 with 24K
>>> bytes of memory were successful.  Attempts to boot with 16K bytes of
>>> memory were unsuccessful.  An RK05 was used as the disk drive since
>>> it is close to the smallest device driver.  The answer to your question
>>> about using 16K bytes of memory is NO for all versions of RT-11 
>>> starting with
>>> V05.00 or RT-11.
>>> Attempts to boot from RT11SJ.SYS under V04.00 of RT-11 with 24K
>>> bytes of memory were successful.  Attempts to boot with 16K bytes of
>>> memory were also successful.  An RK05 was used as the disk drive.  The
>>> error message "Insufficient memory" is displayed, but some useful work
>>> might be done with just 16K bytes of memory. However, you did not
>>> ask if useful work being done was one of the criteria?
>>> NOTE that I used the Ersatz-11 emulator to check the above details,
>>> so there might be a difference with actual hardware.
>>> If you have any more questions, please ask.
>>> Jerome Fine
>> Thanks for the details.  I had been trying to boot rt-11 v5.3 on a 
>> 16k core
>> 11/40 using RL11 (rl02) and it did not work.   The system was unable to
>> complete the initialization.  CPU diagnostics passed, I could load BASIC
>> papertape.  RL11 working correctly.  In this context I posted my 
>> question.
>> After I posted my message here I loaded up simh and emulated an 11 with
>> 32k.  RT-11 v5.3 disk boots.  When I re-built the system and reduced to
>> 16k, I could not boot, bombed.
>> One thing to remember is 16KW in a pdp11 is not the same thing that simh
>> refers to when one sets the CPU to 16K.  WWW do not all make this
>> distinction clearly.  I get it, just making this comment for future 
>> readers
>> of this thread.
>> Bill 
> RT-11 v5.03 single job monitor boots fine and runs in just 32KB (16KW) 
> of memory.
> You need to be more specific about how you specify the memory 
> configuration (words vs bytes).
> DEC routinely specified everything in KW (words) but most users and 
> tools use KB (bytes) nowadays.
> Note that to force RT11SJ (vs RT11FB) to boot on the below image I 
> booted first using FB
> in a larger memory configuration, did a:
> to force it to boot using the SJ monitor the next time.
> Don

NOTE that while the above command is REQUIRED to perform a
hardware boot (from boot ROMs on real hardware or from
within the SimH emulator.  Starting at least with V04.00 of RT-11,
a software boot (which uses DUP.SAV) is supported from within
RT-11 from within any disk (with the files required to support being
a System Disk) to boot any specific monitor file (in this example
RT11SJ.SYS) using the RT-11 command:

Thus even if there has been the RT-11 command to set up a
boot block on a specific disk for a specific RT-11 monitor
file, it is possible to override the boot block and use any
qualified RT-11 monitor file via an RT-11 software boot
(which uses DUP.SAV).

It is also possible from within RT-11 to force the use of the Primary
Boot Code (which is placed in block zero via the COPY/BOOT
command) via the RT-11 command:
If the user includes a specific monitor in the command:
then the specified monitor file is ignored and the boot code in
block zero of DL1: (placed there via the COPY/BOOT command)
is used instead along with the actual monitor file that had been
specified during the COPY/BOOT command.

> PDP-11 simulator V4.0-0 Beta        git commit id: 4065f47f

This portion of my reply contains many questions.  If possible,
answers to all of them would be appreciated, not just the first

Is this the latest version of SimH?  Also, is is possible to support
a VT100 display.  I have heard that telnet can be used, but I have
never been able to do so.  Since I always use the RT-11 SL:
(Single Line Editor) device driver to support a command stack,
it is essential to support a VT100 display, etc. in order to use
the ARROW keys to move the cursor around.  Is it possible
to support VT100 escape sequences when SimH is being used?
If so, how is that done in general and what specific programs
are required along with the specific commands to implement?
I would need to know how to do this from a 64-bit Windows 10
point of view since that is the only system that I will have available
after the Windows 98SE system that I currently use to run RT-11
is no longer available.  As a default, Ersatz-11 supports running
via the Win32 variant under a 64-bit Windows 10 system.

> CPU     11/34, FPP, idle disabled, autoconfiguration enabled
>         32KB
> NOTE: ctrl-E to exit to SIMH monitor
> sim> boot rl1
> RT-11SJ (S) V05.03
> .sho all

If I remember correctly, the above RT-11 command may be incorrect.
I seem to remember that the following output is displayed as a result of
the RT-11 command:
unless, of course, the rest of the display was omitted and there was
much more actually output.

> RT-11SJ (S) V05.03
> Booted from DL1:RT11SJ
> USR   is set SWAP
> EXIT  is set SWAP
> KMON  is set NOIND
> TT    is set NOQUIET
> ERROR is set ERROR
> SL    is set OFF
> EDIT  is set KED
> KMON nesting depth is 3
> PDP 11/34 Processor
> 32KB of memory
> FP11 Hardware Floating Point Unit
> Extended Instruction Set (EIS)
> Memory Management Unit
> 60 Cycle System Clock

Jerome Fine

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