NAME

boot procedures − UNIX startup

DESCRIPTION

How to start UNIX.  UNIX is started by placing it in memory at location zero and transferring to zero.  Since the system is not reenterable, it is necessary to read it in from disk or tape. 

To boot from disk: type the console command “BOOT” (which may be abbreviated “B”) when the console is in LSI-11 mode.  It may be necessary to type control-P to gain the attention of the LSI-11.  This loads and executes a standalone boot program boot off the floppy.  The boot program relocates itself into high memory, and types a ‘:’ as a prompt on the console.  It then reads from the console a device specification (see below) followed immediately by a pathname.  Boot finds the corresponding file on the given device, loads that file into memory location zero, and starts the program at the entry address specified in the program header (after clearing off the high bit of the specified entry address.)  Normal line editing character can be used in specifying the pathname. 

If you have an rp06 or rm03 disk and wish to boot off of a file system which starts at cylinder 0 of unit 0, you can type “hp(0,0)vmunix” to the boot prompt.  On Ernie Co-vax, “up(0,0)vmunix” would specify a UNIBUS ampex 9300 drive. 

Device specifications.  A device specificaion has the following form:

device(unit, minor)

where device is the type of the device to be searched, unit is the unit number of the device, and minor is the minor device index.  The following list of supported devices may vary from installation to installation:

rpRP06 or RM03 on MASSBUS
upAMPEX 9300 on UNIBUS
htTE16

For tapes, the minor device number gives a file offset. 

Emergency bootstraps.  If the console BOOT command does not work, here is a position-independent program which will read the boot block (block 0) from a RP06 or RM03 disk, on the MASSBUSS; the boot block will then boot in the file /boot off the file system at cylinder 0 of the RP, in the same way that the console floppy would bring the program in. 

RP06 disk (MBA 0, drive 0)
00009fdemoval∗$0x20010000,r1# MBA 0
  512001
d0      movl$1,4(r1)# initialize MBA
  04a101
d0      movl$0x13,0x400(r1)# volume valid
0400c113
10008f32cvtwl$0x1000,0x424(r1)# 16-bit format
  0424c1
d4      clrl12(r1)# map reg. 0, offset 0
    0ca1
8fd0    movl$0x80000000,0x800(r1)# valid, page 0/0
80000000
  0800c1
32      cvtwl$-512,16(r1)# byte count
a1fe008f
      10
28c1d4  clrl0x428(r1)# cylinder
      04
14c1d4  clrl0x414(r1)# sector, track
      04
c139d0  movl$0x39,0x400(r1)# read 1 block
    0400
  00    halt

To boot from magnetic tape:  The tp(1) command places the bootstrap program mboot on block 0 of the tape.  When read into memory at location 0 and executed, mboot prompts with an equal sign ‘=’, reads a file name from the console, then loads and executes that file from the tp tape.  Unfortunately DEC does not provide a console command to read a block from tape to memory.  Here is a position-independent program which does:

TM03 magtape (MBA 1, drive 0) from load point:
20009fdemoval∗$0x20012000,r1# MBA 1
  512001
d0      movl$1,4(r1)# initialize
  04a101
32      cvtwl$0x14c0,0x424(r1)# drive characteristics
c114c08f
    0424
a1d4    clrl12(r1)# map reg. 0, offset 0
      0c
008fd0  movl$0x80000000,0x800(r1)# valid, page 0/0
c1800000
    0800
8f32    cvtwl$-512,16(r1)# byte count
10a1fe00
00c139d0movl$0x39,0x400(r1)# read 1 block
      04
    00  halt
Then give the console command “START 0\r”.

mboot does not perform character erase and line kill editing.  Instead, it starts over with the prompt for file name whenever the requested file cannot be found. 

Be sure that mboot exists whenever a tp tape is made.  Remember to put an appropriate block 0 boot and a /boot in file systems when running mkfs.

FILES

/vmunixUNIX code
/usr/mdec/ubootrp disk bootstrap
/bootbackup system bootstrap
/usr/mdec/mboot tp magtape bootstrap

SEE ALSO

tp(1), init.vm(8)

3rd Berkeley Distribution  —  VAX-11