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 rela-
       tively 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, relo-
       cates  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 pathname.  Boot finds the corresponding file on the given device, loads that file into memory location zero, sets up  mem-
       ory management 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 appropriate 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 mem-
       ory.   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 constituting 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)