.TH BOOT 8.SH NAMEboot \- startup procedures.SH DESCRIPTIONA PDP11/45 and PDP11/70 UNIX system is started bya two-stage process.The first is a primary bootstrapwhich is able to read in relatively small stand-alone programs;the second (called.IR boot )is used to read in the system itself..PPThe primary bootstrap must residein the otherwise unused block zero of the boot device.It can be read in and started by the standard ROMprograms,or if necessary by keying in a small startup routine.This program is capable of loading type 407 executablefiles (not shared, not separate I&D).The user types on the system consolethe name of the program wished, in this case.IR boot ,followed by a carriage return;the named program is retrieved from the file systemthat 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 noprovision is made for correcting typographical errors..PPThe second step, called.I boot,actually brings in the system.When read into location 0 and executed,.I bootsets up memory management, relocates itself intohigh memory, and types a `:' on the console.Then itreads from the consolea device specification (see below) followed immediately bya pathname..I Bootfinds 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 executing a `trap' instruction.Normalline editing characters can be used..PPConventionally, the name of the secondary boot programis `/boot' and the name of the current version of the systemis `/unix'.Then, the recipe is:.TP1)Load block 0 of the boot device by fiddling with theconsole keys as appropriate for your hardware.If you have no appropriate ROM, some programs suitablefor manual use are given below..TP2)Type.IR boot ..TP3)When the prompt is given, type.br	hp(0,0)unix.bror.br	rp(0,0)unix.brdepending on whether you are loading from an RP04/5/6 or an RP03respectively.The first 0 indicates the physical unit number;the second indicatesthe block number of the beginning of the logical filesystem to be searched.(See below)..PPWhen the system is running, it types a `#' prompt.After doing any file system checks and setting the date.RI ( date (8))a multi-user system is brought up by typing an EOT(control-d)in response to the `#' prompt..PP.B Device specifications.A device specification has the following form:.IP " "device(unit,offset).LPwhere.I deviceis the type of the device to be searched,.I unitis the unit number of the device,and .I offsetis the block offset of the file system on the device..I Deviceis one of the following.br.nf	rp	RP03	hp	RP04/5/6	rk	RK05.fiFor example, the specification.IP " "hp(1,7000).LPindicates an RP03 disk, unit 1, and the file system foundstarting at block 7000 (cylinder 35)..PP.SM.B ROM.B programs.The following programs to call the primary bootstrapmay be installed in read-only memoriesor manually keyed into main memory.Each program is position-independentbut should be placed well above location 0so it will not be overwritten.Each reads a block from thebeginning of a device into core locationzero.The octal words constituting the program arelisted on the left..PP.ne 5.nf.if n .ta 3 11 15 23 38.if t .ta .3i 1i 1.4i 2i 3.5iRK (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.PP.ne 11RP (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.DT.SH FILES/unix \- system code.br/usr/mdec/rpuboot, /usr/mdec/hpuboot \- copies of primary bootstrap.br/boot \- second stage bootstrap.SH "SEE ALSO"init(8)