Vtserver 32MB limit

Dennis Boone drb at msu.edu
Wed Feb 28 10:46:01 CST 2018

 > I've been using vtserver to transfer an OS to a minimal pdp11 (only a
 > HD and console port so far). Works fine but it has a well-documented
 > 32MB file limit. This website
 > http://home.windstream.net/engdahl/vtserver.htm mentions some hacks
 > but I've been unable to contact the author. Anyone have details of
 > either the code or author?

Warren Toomey's email address can probably be found through tuhs.org.
He is the original author.  Jonathan Engdahl's homepage shows his email
address.  His changes are explained at the page you linked.

The 32MB limit arises due to the use of 16 bit block number fields in
the protocol.  There was a block number compression scheme in the source
(may have been conditionally compiled, memory fades), but it didn't seem
to work properly.  I needed to read RD54 drives, so I committed a hack
upon the thing, expanding the block number field to 32 bits.  I had a
bit of trouble with the first-boot stuff that vtserver toggles into ODT,
so I hacked on that too.  The windows side of this hacked version is
completely untested.  I never packaged this hack properly: no comments,
no updates to the documentation, etc.  But if it's useful, you can find
it here:



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