pdc

pdc - Processor Dependent Code (pdc) overview.

 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 an HP-IB      card, the next number is the HP-IB address, followed by the unit      number of the device if the device supports units.  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      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 mnenomic.           -  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), hpuxboot(1M), isl(1M).