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 pdc(1M)							     pdc(1M)




 NAME
      pdc - processor-dependent code (firmware)

 DESCRIPTION
      pdc is the firmware that implements all processor-dependent
      functionality, including initialization and self-test of the
      processor.  Upon completion, it loads and transfers control to the
      initial system loader (isl(1M)).	Firmware behavior varies somewhat,
      depending on the hardware series as described below.

    Series 800 Behavior
      To load isl from an external medium, pdc must know the particular
      device on which isl resides.  Typically the device is identified by
      the Primary Boot Path that is maintained by pdc in Stable Storage.  A
      path specification is a series of decimal numbers each suffixed by
      '/', indicating bus converters, followed by a series of decimal
      numbers separated by '.', indicating the various card and slot numbers
      and addresses.  The first number, not specifying a bus converter, is
      the MID-BUS module number (that is, slot number times four) and
      followed by the CIO slot number.	If the CIO slot contains a terminal
      card, the next number is the port number, which must be zero for the
      console.

      When the processor is reset after initialization and self-test
      complete, pdc reads the Console Path from Stable Storage, and attempts
      to initialize the console device.	 If the initialization fails, pdc
      attempts to find and initialize a console device.	 Algorithms used to
      find a console device are model-dependent.  pdc then announces the
      Primary Boot, Alternate Boot, and Console Paths.

      If autoboot (see isl(1M)) is enabled, pdc provides a 10-second delay,
      during which time the operator can override the autoboot sequence by
      typing any character on the console.  If the operator does not
      interrupt this process, pdc initializes and reads isl from the Primary
      Boot Path.  On models that support autosearch, if this path is not
      valid and autosearch (see isl(1M)) is enabled, pdc then searches
      through the MID-BUS modules and CIO slots to find a bootable medium.
      Currently, autosearch is only implemented on the model 825.

      If the autoboot sequence is unsuccessful, overridden by the operator,
      or not enabled in the first place, pdc interactively prompts the
      operator for the Boot Path to use.  Any required path components that
      are not supplied default to zero.

      The Primary Boot, Alternate Boot, and Console Paths as well as
      autoboot and autosearch enable can be modified via isl.

    Series 700 Behavior
      To load isl from an external medium, pdc must know the particular
      device on which isl resides.  Typically the device is identified by
      the Primary Boot Path that is maintained by pdc in Stable Storage.  A



 Hewlett-Packard Company	    - 1 -   HP-UX Release 11i: November 2000






 pdc(1M)							     pdc(1M)




      path specification is an I/O subsystem mnemonic that varies according
      to hardware model.

      When the processor is reset after initialization and self-test
      complete, pdc reads the Console Path from Stable Storage, and attempts
      to initialize the console device.	 If the initialization fails, pdc
      attempts to find and initialize a console device.	 Algorithms used to
      find a console device vary according to hardware model.

      If autoboot and autosearch (see isl(1M)) are enabled, pdc waits for
      approximately 10 seconds during which time the operator can override
      the autoboot sequence pressing and holding the ESC (escape) key on the
      console.

      The system then begins a search for potentially bootable devices.	 If
      allowed to complete, a list of potentially bootable devices is
      displayed, labeled with abbreviated path identifiers (P0, P1, etc).  A
      simple menu is then displayed where the user can:

	   +  Boot a specific device, using the abbreviated path identifier,
	      or the full mnemonic.

	   +  Start a device search where the contents are searched for IPL
	      images (note the first search only identified devices and did
	      not check the contents).

	   +  Enter the boot administration level.

	   +  Exit the menu and return to autobooting

	   +  Get help on choices

      The search of potentially bootable devices can be aborted by pressing
      and holding the escape key.  The search for device contents can also
      be aborted by pressing and holding the escape key.

      If the operator does not interrupt the search process, pdc initializes
      and reads isl from the Primary Boot Path.

      If the autoboot sequence is unsuccessful, overridden by the operator,
      or not enabled in the first place, pdc executes the device search and
      enters the menu described above.

      The Primary Boot, Alternate Boot, and Console Paths as well as
      autoboot and autosearch enable can be modified via isl or at the pdc
      boot administration level.

 SEE ALSO
      boot(1M) isl(1M).





 Hewlett-Packard Company	    - 2 -   HP-UX Release 11i: November 2000