1BOOT(8)                     System Manager's Manual                    BOOT(8)
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NAME

6       boot - startup procedures
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DESCRIPTION

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.
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14       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.
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25       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.
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34       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:
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38       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.
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42       2)     Type boot.
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44       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
53       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.
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58       Device specifications.  A device specification has the following form:
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60              device(unit,offset)
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62       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
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70              hp(1,7000)
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72       indicates an RP03 disk, unit 1, and the file system found  starting  at
73       block 7000 (cylinder 35).
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75       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.
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82       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
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93       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
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FILES

107       /unix - system code
108       /usr/mdec/rpuboot, /usr/mdec/hpuboot - copies of primary bootstrap
109       /boot - second stage bootstrap
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SEE ALSO

112       init(8)
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114
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116                                                                       BOOT(8)
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