This directory contains a modified version of Stamerjohn's
famous 11m virtual disk driver package.

Herein is a version of AVD which allows one to assign a
virtual disk by specifying the starting block number and
the extent. We use this along with our AED-8000 disk
controller to simulate an rp06 with 1200 or so cylinders
(rp06 has only about 800). Thus The first 2/3rds of our
disk appears to rsx as an exact replica of the rp06 and
the last third (accessable by patching the ucb of the
driver to permit 515000 blocks) is a virtual disk. Thus we
can hardware boot it without making any patches to boot
and sav as well as we can use preserve on the first 2/3's
(we never backup the virtual disk - use it just for
scratch).

One other possibility is to assign a virtual disk which
overlaps the actual disk BUT AS READ-ONLY. We use this
whenever we use BRU (after it wiped us out one time). Also
one can then read any where on the disk one wants (say
with dump) to look at the boot block etc. - all with the
disk up and running for other users.

Of course you need the Virtual disk package from earlier
decus tapes. If you are not familiar with the virtual disk
driver I recommend you look into it. It is one of the most
useful programs (especially for its size) that I have come
across on the tapes. (When I asked Dec why they wouldn't
support it they said: 'We intend to write one ourselves',
but I doubt if it will ever be as good.)
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; MCR COMMAND LINE IN FORM SHOWN BELOW.
;
; avl VDN:=/SW
;
; VDN: VIRTUAL DISK TO ASSIGN.
; /SW SWITCHES:
;
; /RO ALLOW ONLY READ ACCESS (optional)
; /be:beginblock (necessary)
; /si:size (necessary)
;
; OUTPUT:
;
; VIRTUAL DISK ASSIGNED TO area on disk OR ERROR MESSAGE
; OUTPUT TO USER'S TERMINAL.
;
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