Making an RT-11 boot disk

David Betz dbetz at
Tue Apr 10 19:49:11 CDT 2007

>>> Is it possible to put more than one partition on the drive or
>>> to convince RT-11 to use more than 32mb of the disk?
>> RT-11 uses, IIRC, 16-bit block pointers... 65536 x 512 bytes == 32MB,
>> the largest swath of a big drive it can grab in one chunk.  I've  
>> never
>> personally run RT-11 with a disk over 32MB, so I don't know how it's
>> done, but I know it can be done.  It might or might not depend on  
>> what
>> version of RT-11 you have.  I *think* if you have MSCP support, you
>> always have the ability to have multiple partitions on your large
>> drives, but someone with experience on new(ish) hardware should chime
>> in.  The largest machine I ever ran at home was an 11/23 with a  
>> couple
>> of RL drives.  When I did use RT-11 on an 11/73 with a large disk, it
>> was under TSX-11, and without the docs in front of me, I'd  
>> hesitate to
>> quote technique from memory.
>> You should be able to find what you are looking for in the RT-11 docs
>> for versions of RT-11 > 5.4, at least.  Dunno about < 5.4.
>> -ethan
> It is possible... I use an Emulex SCSI controller on my 11/23+ and  
> it works with multiple partition support via MSCP.
> Each DU: driver can control several partitions (7?). It has to be  
> configured... Don't know how I did it. But I *think* there was  
> something about a "set" command.

Okay, I think I see how to do it:

set du0 unit=0, part=0
set du1 unit=0, part=1
set du2 unit=0, part=2
set du3 unit=0, part=3

If I do this, I wonder where my RX33 will be assigned. Is it assigned  
du4 since du0-3 are already taken by partitions?

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