term% cat index.txt PREP(8) System Manager's Manual PREP(8)
NAME
prep, format - prepare hard and floppy diskettes
SYNOPSIS
disk/prep [ -ra ] special [ type ]
disk/format [ -t type ] [ -f ] [ -d ] [ -b bfile ] [ -c csize ] [ -l
label ] drive [ files ... ]
DESCRIPTION
A partition table is stored on a hard disk to specify the division of
the physical disk into a set of logical units. On Plan 9 the partition
table is a list of triples: name, starting sector, and ending sector.
The kernel fabricates the first two partitions, disk and partition; the
disk partition records the starting and ending sectors for the whole
disk, and the partition partition, typically the last sector on the
disk, holds the partition table itself.
Special is the maximal prefix of names of the logical units on the
disk, for example #w/hd0. Prep reads and prints the associated parti‐
tion table and then enters a simple interactive mode to control editing
the table.
The options are:
-r (read only) prohibits writing the table on disk.
-a automatically create default partitions if no partition table
already exists. These include partitions for DOS, a boot ker‐
nel, an NVRAM substitute, a kfs(4) file system, and, if room re‐
mains, a swap partition.
Format prepares for use the floppy diskette in the disk file named
drive, for example /dev/fd0disk. The options are:
-f Do not physically format the disc. Used to install an MS-DOS
filesystem on a previously formatted disc. With this option,
drive can be a plain file.
-t specify a density and type of disk to be prepared. The possible
types are:
3½DD 3½" double density, 737280 bytes
3½HD 3½" high density, 1474560 bytes
5¼DD 5¼" double density, 368640 bytes
5¼HD 5¼" high density, 1146880 bytes
The default is the highest possible on the device, unless -f is
used, in which case the default is 3½HD.
-d add MS-DOS parameter block, file access table (FAT), and root
directory to the start of the floppy.
The remaining options have effect only when -d is specified:
-b use the contents of bfile as the bootstrap block installed in
sector 0.
-c use a DOS cluster size of csize sectors when creating the DOS
FAT.
-l add a label when creating the DOS parameter block.
Again under -d, any files listed are added, in order, to the root di‐
rectory of the MS-DOS filesytem. The files are contiguously allocated
and created with the READONLY attribute set.
The file /sys/src/boot/pc/bb is an example of a suitable bfile to make
the disk a boot disk. It gets loaded by the BIOS at 0x7C00, reads the
root directory into address 0x7E00, and looks at the first root direc‐
tory entry. If that file is called B.COM, it uses single sector reads
to load the file into address 0x10000 and then jumps to the loaded file
image.
EXAMPLE
Create a Plan 9 boot floppy on a previously formatted diskette:
disk/format -f -b bb -d /dev/fd0disk /386/b.com
SOURCE
/sys/src/cmd/disk/prep.c
/sys/src/cmd/disk/format.c
/sys/src/boot/pc/bb.s
SEE ALSO
floppy(3), wren(3), b.com(8)
PREP(8)