1BOOT(8) System Manager's Manual BOOT(8)
2
6 boot - startup procedures
7
9 A PDP11/45 and PDP11/70 UNIX system is started by a two-stage process.
10 The first is a primary bootstrap which is able to read in relatively
11 small stand-alone programs; the second (called boot) is used to read in
12 the system itself.
13 The primary bootstrap must reside in the otherwise unused block zero of
15 the boot device. It can be read in and started by the standard ROM
16 programs, or if necessary by keying in a small startup routine. This
17 program is capable of loading type 407 executable files (not shared,
18 not separate I&D). The user types on the system console the name of
19 the program wished, in this case boot, followed by a carriage return;
20 the named program is retrieved from the file system that starts at
21 block 0 of drive 0 of the boot device. No prompt is given, no diagnos‐
22 tic results if the file cannot be found, and no provision is made for
23 correcting typographical errors.
24 The second step, called boot, actually brings in the system. When read
26 into location 0 and executed, boot sets up memory management, relocates
27 itself into high memory, and types a `:' on the console. Then it reads
28 from the console a device specification (see below) followed immedi‐
29 ately by a pathname. Boot finds the corresponding file on the given
30 device, loads that file into memory location zero, sets up memory man‐
31 agement as required, and calls the program by executing a `trap'
32 instruction. Normal line editing characters can be used.
33 Conventionally, the name of the secondary boot program is `/boot' and
35 the name of the current version of the system is `/unix'. Then, the
36 recipe is:
37 1) Load block 0 of the boot device by fiddling with the console
39 keys as appropriate for your hardware. If you have no appropri‐
40 ate ROM, some programs suitable for manual use are given below.
41 2) Type boot.
43 3) When the prompt is given, type
45 hp(0,0)unix
46 or
47 rp(0,0)unix
48 depending on whether you are loading from an RP04/5/6 or an RP03
49 respectively. The first 0 indicates the physical unit number;
50 the second indicates the block number of the beginning of the
51 logical file system to be searched. (See below).
52 When the system is running, it types a `#' prompt. After doing any
54 file system checks and setting the date (date(8)) a multi-user system
55 is brought up by typing an EOT (control-d) in response to the `#'
56 prompt.
57 Device specifications. A device specification has the following form:
59 device(unit,offset)
61 where device is the type of the device to be searched, unit is the unit
63 number of the device, and offset is the block offset of the file system
64 on the device. Device is one of the following
65 rp RP03
66 hp RP04/5/6
67 rk RK05
68 For example, the specification
69 hp(1,7000)
71 indicates an RP03 disk, unit 1, and the file system found starting at
73 block 7000 (cylinder 35).
74 ROM programs. The following programs to call the primary bootstrap may
76 be installed in read-only memories or manually keyed into main memory.
77 Each program is position-independent but should be placed well above
78 location 0 so it will not be overwritten. Each reads a block from the
79 beginning of a device into core location zero. The octal words consti‐
80 tuting the program are listed on the left.
81 RK (drive 0):
83 012700 mov $rkda,r0
84 177412
85 005040 clr -(r0) / rkda cleared by start
86 010040 mov r0,-(r0)
87 012740 mov $5,-(r0)
88 000005
89 105710 1: tstb (r0)
90 002376 bge 1b
91 005007 clr pc
92 RP (drive 0)
94 012700 mov $rpmr,r0
95 176726
96 005040 clr -(r0)
97 005040 clr -(r0)
98 005040 clr -(r0)
99 010040 mov r0,-(r0)
100 012740 mov $5,-(r0)
101 000005
102 105710 1: tstb (r0)
103 002376 bge 1b
104 005007 clr pc
105
107 /unix - system code
108 /usr/mdec/rpuboot, /usr/mdec/hpuboot - copies of primary bootstrap
109 /boot - second stage bootstrap
110
112 init(8)
113 BOOT(8)