
                 USAGE INSTRUCTIONS FOR VIRTUAL DISKS - DV

     1.  RUN DVSET - Changes an unused PUD to DV.  Not needed if you SYSGEN
         with  a  DV  PUD.  If you use DVSET, be sure to change the code to
         reflect the correct PUD address of the  unused  PUD  you  wish  to
         change.
     2.  INS/TAS:VRTACP [11,1]BIGFCP - Installs  an  ACP  for  the  virtual
         disk.   The  system  does  some funny things if you try to use the
         same ACP for both the virtual and real disk.
     3.  INS DV - Installs the handler
     4.  RUN/N DV....  - Loads the handler, which  will  respond  with  the
         prompt

             Virtual Disk File ?

         Enter  the  virtual  disk  filename  followed  by   any   switches
         (described  below).   All  switches  are optional, except for /CR,
         which is required  when  creating  the  virtual  disk  file.   The
         default  filespec is [1,1]VIRTUAL.DSK.  Some switches you may want
         to use are:

         1.  /CR - Create the virtual disk file.
         2.  /EM:XXXX - Emulate the  disk  type  XXXX,  e.g.,  RK07.   This
             switch  is  needed only if you plan to use DSC on your virtual
             disk.  The default for this switch is "Unknown".
         3.  /SI:n - Specifies the size of  the  virtual  disk  in  decimal
             blocks.  The default at disk creation is 20000.
         4.  /LI - Lists the characteristics of the virtual disk (EM and SI
             parameters).

     5.  Enter a Control-C to get PDS back.
     6.  ALLOC DV0:
     7.  INI/PRO:(WO:RWED)/FILE:(WO:RWED) DV0:  Volumeid
     8.  DEALLOC DV0:
     9.  MOU/PROCESSOR:VRTACP DV0:  Volumeid

The virtual disk is now mounted and ready for  use.   You  can  create  new
UIC's, copy and delete files or anything else you do with real disks.

When finished dismount the virtual disk and unload the handler with:

     DISM DV0:  Volumeid
     MCR UNL DV

You can now dismount the real disk (if other than the system disk).

WARNING:  The dismount and unload operations MUST  be  done  in  the  order
indicated.   The  virtual  disk  handler (DV) maintains an open file on the
real disk and MUST be unloaded (to close the file) before you can  dismount
the  real  disk (and logout).  This applies only to the terminal from which
the handler is loaded.  Once the handler is loaded  and  the  virtual  disk
defined,  other  terminals can mount and dismount the virtual disk at will,
without mounting the real disk.

