SUPERFORMAT(1) manual page

Table of Contents

superformat -d drive [-D dos-drive] [--dd] [--hd] [--2m] [--no2m] [-s sectors] [-H heads] [-t tracks] [-v verbosity-level] [-b begin-track] [-e end-track] [--dosverify] [--noverify] [--verify_later] [-S sizecode] [-G format-gap] [-F final-gap] [-i interleave] [-c chunksize] [-g gap] [-r rate] [--absolute-skew absolute-skew] [--head-skew head-skew] [--track-skew track-skew] [--stretch stretch-factor] [-m margin]

DESCRIPTION

superformat is used to format disks with a capacity of up to 1992K HD or 3984K ED. When the disk is formatted, mformat(1) is automatically called to put an msdos filesystem on it. You may ignore this filesystem, if you don't need it. Be aware, however, that the --2m formats were specifically designed to hold an msdos filesystem, and take advantage from the fact that the msdos filesystem uses redundant sectors on the first track (the FAT, which is represented twice). The second copy of the FAT is not represented on the disk.

OPTIONS

Many options have a long and a short form.

-h --help: Print the help.
-d drive --drive drive: Selects the drive to format. The default is drive 0
-D drive --dosdrive dos-drive: Selects DOS drive letter for mformat(1). or b:). The colon may be omitted. The default is derived from the minor device number. If the drive letter cannot be guessed, and is not given on the command line, mformat is skipped.
-v verbosity-level --verbosity verbosity-level: Sets the verbosity level. 1 prints a dot for each formatted track. 2 prints a changing sign for each formatted track (- for formatting the first head, = for formatting the second head, x for verifying the first head, and + for verifying the second head). 3 prints a complete line listing head and track. 6 and 9 print debugging information.
--dd: Format a double density disk.
--hd: Format a high density disk.
-2 " --2m": Format a high capacity disk readable by the 2mf program. Only use these disks for MS-DOS filesystems. This option is automatically selected when you attempt to format a disk with bigger sectors than usual. If you don't want this (for reliability reasons), use the --no2m option.
-1 " --no2m": Don't use 2m format.
-t tracks --tracks tracks: Describes the number of tracks. Default is 40 or 80, depending on the drive type or the density.
-H heads --heads heads: Describes the number of heads. Default is 2.
-s sectors --sectors sectors: Describe the number sectors. sectors is not the number of physical (big) sectors, but rather the number of equivalent 512-byte sectors. If you ask for more sectors than fit on the disk, superformat groups them automatically into bigger sectors (as long as this is possible), unless you also specify the sizecode option.
-B " --dosverify": Verifies the disk using the mbadblocks(1) program. mbadblocks marks the bad sectors as bad in the FAT. The advantage of this is that disks which are only partially bad can still be used for MS-DOS filesystems.
-V " --verify_later": Verifies the whole disk at the end of the formatting process instead of at each track. Verifying the disk at each track has the advantage of detecting errors early on.
-f " --noverify": Skips the verification altogether.

ADVANCED OPTIONS

These options have sensible default values, so normally you won't need to set them manually.

-b begin_track --begin_track begin_track: Describes the track where to begin formatting. This is useful if the previous formatting failed halfway through. The default is 0.
-e end_track --end_track end_track: Describes where to stop formatting. end_track is the last track to be formatted plus one. This is mainly useful for testing purposes. By default, this is the same as the total number of tracks. When the formatting stops, the final skew is displayed (to be used as absolute skew when you'll continue).
-S sizecode --sizecode sizecode: Set the sector size to be used. The sector size is 128 * 2 ^ sizecode. Sector sizes below 512 bytes are not supported, thus sizecode must be at least 2. By default 512 is assumed, unless you ask for more sectors than would fit with 512 bytes.
--stretch stretch: Set the stretch factor. The stretch factor describes how many physical tracks to skip to get to the next logical track (2 ^ stretch). On double density 5 disks, the tracks are further apart from each other.
-G fmt_gap --format_gap fmt_gap: Set the formatting gap. The formatting gap tells how far the sectors are away from each other. By default, this is chosen so as to evenly distribute the sectors around the circle.
-F final_gap --final_gap final_gap: Set the formatting gap to be used after the last sector.
-i interleave --interleave interleave: Set the sector interleave factor.
-c chunksize --chunksize chunksize: Set the size of the chunks. The chunks are small auxiliary sectors used during formatting. They are used to handle heterogeneous sector sizes (i.e. not all sectors have the same size) and negative formatting gaps.
-r rate --rate rate: Set the raw data transfer rate (which is smaller for double density disks than for high density disks).
-g gap --gap gap: Set the read/write gap.
-m margin --margin margin: Changes the number of bytes left at the end of the physical track. By default, this is 35. Setting this to a smaller value may make disk accesses unbearably slow.

SECTOR SKEWING

In order to maximize the user data transfer rate, the sectors are arranged in such a way that sector 1 of the new track/head comes under the head at the very moment when the drive is ready to read from that track, after having read the previous track. Thus the first sector of the second track is not necessarily near the first sector of the first track. The skew value describes for each track how far sector number 1 is away from the index mark. This skew value changes for each head and track. The amount of this change depends on how fast the disk spins, and on how much time is needed to change the head or the track.

--absolute_skew absolute_skew: Set the absolute skew. (The skew value used for the first formatted track)
--head_skew head_skew: Set the head skew. (The skew added for passing from head 0 to head 1)
--track_skew track_skew: Set the track skew. (The skew added for seeking to the next track)

Example: (absolute skew=3, head skew=1, track skew=2) track 0 head 0: 4,5,6,1,2,3, (skew=3)
track 0 head 1: 3,4,5,6,1,2, (skew=4)

track 1 head 0: 1,2,3,4,5,6, (skew=0)
track 1 head 0: 6,1,2,3,4,5 (skew=1)

track 2 head 0: 4,5,6,1,2,3, (skew=3)
track 2 head 0: 3,4,5,6,1,2, (skew=4)

EXAMPLES

Assume that drive 0 is a 3 and drive 1 a 5.

superformat: Format 1440K disk in drive 0.
superformat -d /dev/fd1: Format a 1200K disk in drive 1.
superformat -d /dev/fd1 -s 18: Format a 1440K disk in drive 1.
superformat --dd: Format a 720K disk in drive 0.
superformat -s21 -t83: Format a 1743K disk in drive 0 (83 tracks times 21 sectors).
superformat -s24 -t83: Format a 1992K disk in drive 0 (83 tracks times 24 "sectors"). There won't be 24 physical 512-byte sectors on the disk, but rather one 8192-byte sector and a 4096-byte sector. superformat will figure out that this is the only format which fits, with that many "sectors". 24 sectors is the absolute maximum, and might not work everywhere.
superformat -s23 --2m: Format a 1840K disk in drive 0. It will have 5 2048-byte sectors, one 1024-byte sector, and one 512-byte sector per track.

All these formats can be autodetected by mtools, using the floppy driver's default settings.

THE FORMATS

For this discussion, let's assume you are using high density 3 disks. Formats can be distinguished by the number of sectors, the size of these sectors and the number of tracks. Normally, you need not indicate the size of the sectors; superformat figures this out for you.

More Sectors

With superformat, it is possible to put more sectors than usual on the disk, just by squeezing them closer together. However, for none of the formats is a bigger byte density used; i.e. within a sector, each byte takes as much space as with the normal format. Only the gaps between the sectors have become smaller. Formats of up to 20 sectors (17 on a 5 disk) can be obtained. These formats are as fast and as reliable as the standard format. These formats can be read under MS DOS with various shareware utilities, and on SunOS with the mtools included in this package (define -DSPARC_ODD).

Sector Interleaving

It is possible to fit 21 sectors (or 18 with a 5 drive) on one track by making the gaps between the sectors even smaller. With this format, the sectors are so close together that the floppy controller is still processing the previous sector when it reaches the header of the next sector. Thus it misses the next sector, and must wait for one more turn, until it shows up again. That's 200 milliseconds per turn, and this would add up to 4.4 seconds for all sectors! To avoid this, sectors are interleaved, i.e. the second sector does not immediately follow the first one. You get: 1,11,2,12,3,13,4,14,5,15,6,16,7,17,8,18,9,19,10,20
Now, the disk is only twice slower instead of 22 times slower.

Interleave is also handled automatically by superformat.

Although this format is twice as slow as the previous formats, it is as reliable, and can also be read under MS DOS and SunOS.

Bigger Sectors

By making bigger sectors, i.e., grouping smaller logical sectors in one big sector, more data fits on the disk, because less space is taken up by the sector headers. (The header of a big sector takes as much space than the header of a small sector, but there are less of them.) superformat automatically groups sectors together when needed. The format with 11 1024-byte sectors is again as fast as the standard format. However, it is less reliable, because a failure is likely to erase a whole sector. So, instead of losing 512 bytes at once (normal sector size), you might lose 1024 byte at once. The biggest format that you can obtain with this method has the equivalent of 11264 byte per track, split up in 11 sectors of 1024 bytes each. Unfortunately, these formats can't be read neither under MS-DOS nor under SunOS.

Mixing Sector Sizes on the Same Track

It is possible to to put sectors of different sizes on one track. The biggest format that you can obtain with this method has the equivalent of 12288 byte per track, split up in a 8192 byte sector and a 4096 byte sector. Mixing sector sizes does not introduce a new unreliability.

2M Formats

These formats are essentially the same as the big sector formats, but their first track is formatted using 18 normal sized sectors. These disks can be read and written with the 2m20 utility under DOS. These disks store only one physical copy of the FAT, and might be less reliable for this reason. If you lose this only copy of the FAT, there is no backup, as is the case on normal disks.

Only one FAT is stored because the first track appears to have 18 sectors to to the applications, and the second copy of the FAT would fall into the missing sectors. That's also the reason why you shouldn't use these formats to store anything else than a DOS filesystem.

The 2m option is automatically selected for disks which have a bigger sector size than usual. If you don't want this (for reliability reasons), select the --no2m option.

The advantage of 2m is that it makes autodetection easier. The first track can be read using the usual parameters, and its boot sector contains the necessary information needed to read the other sectors. Thus, autodetection only needs to probe for the standard formats (one for ED, one for HD and one for DD). One of these formats allows to read the boot sector, and mtools uses the information contained therein to access the rest of the disk.

DIAGNOSTICS

FDC busy, sleeping for a second: When another program accesses a disk drive on the same controller as the one being formatted, superformat has to wait until the other access is finished. If this happens, check whether any other program accesses a drive (or whether a drive is mounted), kill that program (or unmount the drive), and the format should proceed normally.

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SYNOPSIS