HP 3000 Manuals

Configuring Systems for Terminals, Printers, and Other Serial Devices

How Devices Are Owned and Why 

Devices (terminals, printers, plotters, etc.)  are subject to ownership.
If a device is owned by a process, then use of the device by other
processes is restricted.  For instance, when a session owns a terminal,
only the process which initiated the session or its child process, can
access the terminal.

To determine which process owns a device, use the MPE/iX SHOWDEV command.
Asynchronous devices will be listed as one of the following:

   *   Available.  The device is not owned.  Any process that wants to
       claim ownership of the device can do so.  For terminals, this
       means that no one is logged on to the device or no other process
       has programmatically opened the terminal.  For printers, it means
       that the device is not spooled, nor has it been opened by a user
       program.

   *   Unavailable.  The device is owned.  The owner--a job, a session,or
       the system--is also listed.

   *   Spooled.  The device is owned by the spooler while data is being
       transferred between a spoolfile (on disk) and the device.  Other
       processes can access the device through the spooler, but only the
       spooler process owns the device.  Printers and plotters are the
       only asynchronous devices that are spooled.


NOTE  UPS devices are always owned by the system.

MPE/iX 5.5 Documentation