BOOT(8)BOOT(8)NAMEboot - 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 ALSOinit(8)BOOT(8)
