This worked perfectly!

I was able to mount the partitions (as shown below) and actually extract the entire 65K partition to a *.dsk file that SIMH was able to mount and read. This is what I was trying to do.  Get files from the RT11freewarev2 cd into SIMH.  From there I can get them to my real PDP11 hardware.
Some of the files are binary so this process is necessary.

One comment - when you execute a mount command it takes a minute or 2 to decompress the file, so be patient!
One question - How did you know how much to skip?

Thanks for the effort you put into creating FSX.


On 4/29/2022 4:11 PM, Kenneth Gober wrote:
On Wed, Apr 27, 2022 at 10:55 AM Douglas Taylor via cctech <> wrote:

    I wanted to extract some parts of the RT11 Freeware iso file that is
    available on the internet.  The note Tom Shoppa wrote indicates
    that the
    CD has 2 partitions.  When I burned the CD on a windows machine I
    see one partition.

    How to I extract the 2nd partition off the iso?

The second "partition" is just a second copy of all the files on the first partition, except in RT-11 volume format so that it can be mounted directly on an RT-11
system with a CD-ROM drive attached. Since RT-11 volumes are limited to
32MB, larger disks are broken up into 32MB 'logical disks'.  The files are on
logical disks 13 through 19 (i.e. 32MB chunk numbers 13 through 19).

Since it's all the same files, there's little reason to bother looking at the second partition if you are able to mount the first.  However, if you want to do it anyway I have a Windows command-line tool that can be used to access the RT-11 portions of the iso: GitHub - kgober/FSX: File System Exchange, a utility to access data stored in disk images <>

Here are the FSX commands you would use to mount each of the chunks:
FSX> mount r13: rt11freewarev2.iso.gz <skip=416m>
FSX> mount r14: rt11freewarev2.iso.gz <skip=448m>
FSX> mount r15: rt11freewarev2.iso.gz <skip=480m>
FSX> mount r16: rt11freewarev2.iso.gz <skip=512m>
FSX> mount r17: rt11freewarev2.iso.gz <skip=544m>
FSX> mount r18: rt11freewarev2.iso.gz <skip=576m>
FSX> mount r19: rt11freewarev2.iso.gz <skip=608m>

FSX knows about .gz files and will treat the 'skip' option as the offset to
use *after* uncompressing the file.

You can then browse and extract files from each volume:
FSX> dir r19:
 Volume ID: VMS Exchange
 Owner    : SHOPPA
README.TXT    23P 15-Oct-1999 TORS84.DSK 24535P 15-Oct-1999
UCLPLS.DSK   907P 15-Oct-1999 VMSBCK.DSK  1663P 15-Oct-1999
XASSMB.DSK  2036P 15-Oct-1999 DUSTAT.DSK   100P 15-Oct-1999
RT11  .LIS    13P 15-Oct-1999 < UNUSED > 36190
 7 Files, 29277 Blocks
 36190 Free blocks

FSX>type r19:readme.txt
Welcome, RT-11 User, to V2.0 of the RT-11 Freeware CD!
[... remainder removed ...]

FSX>save r19:readme.txt c:readme.txt
R19:README.TXT => c:readme.txt


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