man(1) Manual page archive

     BOOT(8)                                                   BOOT(8)

          boot - startup procedures

          A PDP11/45 and PDP11/70 UNIX system is started by a two-
          stage process.  The first is a primary bootstrap which is
          able to read in relatively small stand-alone programs; the
          second (called boot) is used to read in the system itself.

          The primary bootstrap must reside in the otherwise unused
          block zero of the boot device.  It can be read in and
          started by the standard ROM programs, or if necessary by
          keying in a small startup routine.  This program is capable
          of loading type 407 executable files (not shared, not sepa-
          rate I&D).  The user types on the system console the name of
          the program wished, in this case boot, followed by a car-
          riage return; the named program is retrieved from the file
          system that starts at block 0 of drive 0 of the boot device.
          No prompt is given, no diagnostic results if the file cannot
          be found, and no provision is made for correcting typograph-
          ical errors.

          The second step, called boot, actually brings in the system.
          When read into location 0 and executed, boot sets up memory
          management, relocates itself into high memory, and types a
          `:' on the console.  Then it reads from the console a device
          specification (see below) followed immediately by a path-
          name.  Boot finds the corresponding file on the given
          device, loads that file into memory location zero, sets up
          memory management as required, and calls the program by exe-
          cuting a `trap' instruction.  Normal line editing characters
          can be used.

          Conventionally, the name of the secondary boot program is
          `/boot' and the name of the current version of the system is
          `/unix'.  Then, the recipe is:

          1)   Load block 0 of the boot device by fiddling with the
               console keys as appropriate for your hardware.  If you
               have no appropriate ROM, some programs suitable for
               manual use are given below.

          2)   Type boot.

          3)   When the prompt is given, type
               depending on whether you are loading from an RP04/5/6
               or an RP03 respectively.  The first 0 indicates the

     BOOT(8)                                                   BOOT(8)

               physical unit number; the second indicates the block
               number of the beginning of the logical file system to
               be searched.  (See below).

          When the system is running, it types a `#' prompt.  After
          doing any file system checks and setting the date (date(8))
          a multi-user system is brought up by typing an EOT
          (control-d) in response to the `#' prompt.

          Device specifications. A device specification has the fol-
          lowing form:


          where device is the type of the device to be searched, unit
          is the unit number of the device, and offset is the block
          offset of the file system on the device.  Device is one of
          the following
               rp   RP03
               hp   RP04/5/6
               rk   RK05
          For example, the specification


          indicates an RP03 disk, unit 1, and the file system found
          starting at block 7000 (cylinder 35).

          ROM programs. The following programs to call the primary
          bootstrap may be installed in read-only memories or manually
          keyed into main memory.  Each program is position-
          independent but should be placed well above location 0 so it
          will not be overwritten.  Each reads a block from the begin-
          ning of a device into core location zero.  The octal words
          constituting the program are listed on the left.

          RK (drive 0):
             012700      mov     $rkda,r0
             005040      clr     -(r0)          / rkda cleared by start
             010040      mov     r0,-(r0)
             012740      mov     $5,-(r0)
             105710  1:  tstb    (r0)
             002376      bge     1b
             005007      clr     pc

     BOOT(8)                                                   BOOT(8)

          RP (drive 0)
             012700      mov     $rpmr,r0
             005040      clr     -(r0)
             005040      clr     -(r0)
             005040      clr     -(r0)
             010040      mov     r0,-(r0)
             012740      mov     $5,-(r0)
             105710  1:  tstb    (r0)
             002376      bge     1b
             005007      clr     pc

          /unix - system code
          /usr/mdec/rpuboot, /usr/mdec/hpuboot - copies of primary
          /boot - second stage bootstrap