PWB1/usr/man/man8/diskboot.8

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.th "DISK BOOT" VIII 5/31/77
.sh NAME
diskboot \*- disk bootstrap programs
.sh DESCRIPTION
There are two versions of the disk bootstrap program,
.ul
uboot.
One handles RP03 type drives and the other RP04
type drives.
Otherwise, the versions are functionally equivalent.
.s3
The program must be located in block 0 of the disk pack.
The space available for the program is thus only one block (256 words)
which severely constrains the amount of error handling.
Block 0 is unused by the UNIX file system, so this
does not affect normal file system operation.
To boot, the program must be read into memory
starting at address 0 and started at address 0.
This may be accomplished by standard
.if t \s-2DEC\s+2\(rg
.if n DEC (Rg.)
ROM bootstraps,
special ROM bootstraps, or manual procedures.
.s3
After initial load, the program relocates itself to high
core as specified when assembled (typically 24K words,
maximum of 28K).
Next, memory below the program is cleared and the prompt '#'
is typed on the console.
A two digit field specifying the file system to use is expected.
The first digit indicates which drive to use and the second digit
which logical section of the pack to use.
For example, 24 would correspond to /dev/rp24, or
drive 2, section 4.
By convention, section 0 always starts at cylinder 0 and is safest
to use.
No error checking is done on this field, invalid data will
cause unpredictable results.
Also, there is no error checking on disk reads.
.s3
After the file system select, the program prompts with a `='.
The user must then enter the UNIX pathname of the desired file.
The `#' character will erase the last character typed,
the `@' character will kill the entire line, and `A' through `Z' is translated to `a'
through `z'.
Also, carriage return (CR) is mapped into line feed (LF) on input, and
LF is output as CR-LF.
The upper-case to lower-case conversion is used
to handle upper-case-only terminals such as
the
.if t \s-2TELETYPE\s+2\(rg
.if n TELETYPE(Rg.)
Model 33
or the
\s-2DEC\s+2
LA30.
Therefore, a file name with upper case characters cannot be
booted using this procedure.
.s3
After the name has been completely entered by typing CR or LF,
the program searches the file system specified for the pathname.
Note, the pathname may be any valid UNIX file system pathname.
If the file does not exist, or if the file is a directory or special file,
the bootstrap starts over and prompts `#'.
Otherwise, the file is read into memory starting at address 0.
If address 0 contains 000\ 407, a UNIX a.out program is assumed and the first 8 words are stripped off by
relocating the loaded program toward address 0.
Finally, a jump to address 0 is done by executing "jsr\ pc,*$0".
.sh FILES
/usr/mdec/uboot -
disk bootstrap
.br
/sys/source/util/rp03boot.s - RP03 source
.br
/sys/source/util/rp04boot.s - RP04 source
.sh "SEE ALSO"
a.out(V), fs(V), unixboot(VIII)