BOOT(8) 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 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
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
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:
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 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
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
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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)