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BOOT(8)                     System Manager's Manual                    BOOT(8)



NAME
       boot - startup procedures

DESCRIPTION
       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 separate I&D).  The user types on the system console  the  name  of
       the  program  wished, in this case boot, followed by a carriage 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 diagnos-
       tic results if the file cannot be found, and no provision is  made  for
       correcting typographical 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  immedi-
       ately  by  a  pathname.  Boot finds the corresponding file on the given
       device, loads that file into memory location zero, sets up memory  man-
       agement  as  required,  and  calls  the  program  by executing 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 appropri-
              ate ROM, some programs suitable for manual use are given below.

       2)     Type boot.

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

              device(unit,offset)

       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

              hp(1,7000)

       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
       beginning of a device into core location zero.  The octal words consti-
       tuting the program are listed on the left.

       RK (drive 0):
          012700      mov     $rkda,r0
          177412
          005040      clr     -(r0)          / rkda cleared by start
          010040      mov     r0,-(r0)
          012740      mov     $5,-(r0)
          000005
          105710  1:  tstb    (r0)
          002376      bge     1b
          005007      clr     pc

       RP (drive 0)
          012700      mov     $rpmr,r0
          176726
          005040      clr     -(r0)
          005040      clr     -(r0)
          005040      clr     -(r0)
          010040      mov     r0,-(r0)
          012740      mov     $5,-(r0)
          000005
          105710  1:  tstb    (r0)
          002376      bge     1b
          005007      clr     pc

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

SEE ALSO
       init(8)



                                                                       BOOT(8)