BOOT PROCEDURES (VIII) 2/6/73 BOOT PROCEDURES (VIII)
NAME bos, maki, vcboot, msys, et al.
DESCRIPTION
On the RF disk, the highest 16K words are reserved for
stand-alone programs. These 16K words are allocated as
follows:
bos (1K)
Warm UNIX (7K)
Cold UNIX (8K)
The program bos (Bootstrap Operating System) examines the
console switches and executes one of several internal
programs depending on the setting. The following set-
tings are currently recognized:
??? Will read Warm UNIX from the RF into core loca-
tion 0 and transfer to 600.
1 Will read Cold UNIX from the RF into core loca-
tion 0 and transfer to 600.
10 Will dump all of memory from core location 0 onto
DECtape drive 7 and then halt.
20 Will read 256 words from RK0 into core 0 and
transfer to zero. This is the procedure to boot
DOS from an RK.
40 This is the same as 10 above, but instead of
halting, UNIX warm is loaded.
0 Will load a standard UNIX binary paper tape into
core location 0 and transfer to 0.
77500 Will load the standard DEC absolute and binary
loaders and transfer to 77500.
All manual methods of booting the system involve manipu-
lation of the console switches. In order for this to be
possible, the panel must be unlocked and the machine must
be halted. Also, remember that at the time UNIX comes
up, the console switches must contain 773030 for a
single-user system; anything else gives a multi-user sys-
tem.
There are four temperatures of boots. They are:
Hot boot: restart the system without refreshing its
code, that is simply by transferring to its start.
The only use for this procedure is if the system has
been patched and one doesn't wish to redo the
patches. The procedure is:
600 in switches
Load address
(773030 in switches for single-user system)
start
Warm boot: refresh system code from the RF disk, but
the "panic" routine must be in core. Best for gen-
eral use if it works, since outstanding I/O is
cleaned up. Procedure:
602 in switches
load address
(773030 in switches for single-user system)
start (flushes any I/O, then executes bos)
Cool boot: RF disk is OK, but nothing in core. Pro-
cedure:
UTIL DECtape on drive 0
773030 in switches
load address
(602 in switches for multi-user system)
start
type "boot" on console tty to load bos
Cold boot: nothing in core, nothing on RF. Best to
have an expert around for this one. Procedure:
INIT DECtape on drive 0
773030 in switches
load address
1 in switches
start
(machine halts. last chance to preserve RF!)
773030 in switches
continue
(reads in basic files)
UNIX is then up, but for various reasons, one should
do a warm boot (single user) right away. At this
point also, one might consider whether the INIT tape
UNIX is the latest version. If there is reason for
doubt, mount the /sys disk pack, change to directory
/sys/sys, do "msys u unix", and reboot. Then get the
/bin-/etc-/lib tape which contains the rest of of the
RF disk, and do an "mt x". Conceivably, "create er-
rors" due to lack of some directories will occur;
make the directories, then try again. Set the date
correctly; the system starts off at time 0.
At this point UNIX is in full operation and can be
rebooted for a multi-user system.
Here is what happens during a cold boot: the INIT tape
contains a program called vcboot. The ROM program reads
vcboot from the tape into core location 0 and transfers
to it. vcboot then reads 16K words from the DECtape
(blocks 1-32) and copies the data to the highest 16K
words of the RF. Thus this initializes the read-only
part of the RF. vcboot then reads in bos and executes
it. bos reads in Cold UNIX and executes that. Cold UNIX
halts for a last chance before it completely initializes
the RF file system. When continue is pressed, Cold UNIX
initializes the RF. It then reads the DECtape for ini-
tialization files starting from block 33. Normal opera-
tion then commences with the execution of "/etc/init".
The INIT tape is made by the program maki running under
UNIX. maki writes vcboot on block 0 of /dev/tap7. It
then copies the RF 16K words (using /dev/rf0) onto blocks
1 thru 32. It has internally a list of files to be
copied from block 33 on. This list follows:
/etc/init
/bin/chmod
/bin/date
/bin/login
/bin/ls
/bin/mkdir
/etc/mount
/bin/sh
/bin/tap
/bin/mt
Thus this is the set of programs available after a cold
boot. init and sh are mandatory. For multi-user UNIX,
getty and login are also necessary. mkdir is necessary
due to a bug in tap. mt, tap and mount are useful to
bring in new files. As soon as possible, date should be
done. That leaves ls and chmod as frosting.
The last link in this incestuous daisy chain is the pro-
gram msys.
msys char file
will copy the file file onto the RF read only slot speci-
fied by the character char. Char is taken from the fol-
lowing set:
b bos
u Warm UNIX
1 Cold UNIX
FILES /dev/rf0, /dev/tap?
SEE ALSO init(VII), tap(I), sh(I), mkdir(I)
DIAGNOSTICS --
BUGS This section is very configuration dependent.