Disks straight out of the package need to be formatted, that is have tracks and sectors defined so DOS can find programs and data on the disk.

The command syntax is below (only the most useful options are shown).

FORMAT d: /s /u

where

• d: defines the disk that will be formatted
• /s puts the DOS system on disk to make it bootable
• /u specifies an unconditional format (can't unformat the disk)

An example:

Problem: Format the disk in drive A: without UNFORMAT information.

Answer: The proper command is:

C>FORMAT A: /U

In order, you are asked to confirm a disk is present for formatting, then told to what capacity the disk will be formatted (press Control-C to stop the format if this is not correct), then you are given a report on format progress. At the end you are asked for a volume label (optional) and then given a report on the success of the format in terms of the number of bytes on the disk. A serial number is assigned by DOS. It is based on system time and will likely never be the same on two individual disks.

Additional Comments

Some microcomputers have 1.2 megabyte 5.25" disk drives. There is the temptation to use 360 kilobyte disks in those drives; don't do it. The track width is smaller and if you then put the 360K disks into a 360K drive, they may not work properly. Likewise, you cannot use the high density floppy disks themselves in 360K drives. The magnetic properties of the disk are such that the 360K drives won't format them.

With the introduction of 3.5" drives, higher versions of DOS are required to correctly support the new formats. The 3.5" drives come in two sizes: 720K and 1.4MB.

Unlike the 1.2MB/360K drives disks, it is possible to format to 720K in a 1.4MB 3.5" drive. All you have to do is tell the FORMAT command the track/sector combination you need:

FORMAT A: /F:720 (this tells DOS to format the disk in drive A: to 720K)

Not all versions of DOS support higher capacity disks. For example, DOS 3.2 introduced support for 3.5-inch disks, but only at 720K format. In order to format a 3.5-inch disk at 1.44MB you will need DOS 3.3 or later.

Checking the Disk

Now and again it is useful to check the integrity of the disk directory and file allocation table (FAT). The FAT is so important to the disk that there are two copies of it on each disk.

The CHKDSK program does this for you. The basic format is:

CHKDSK d:filename.ext /f /v

Using the filename causes it to be checked for continuity (i.e., being stored on contiguous sectors on the disk for more efficient access).

• /f tells DOS to automatically fix the FAT and other problems
• /v is a verbose mode that shows progress as disk checking is taking place

Example:

Only use the version of CHKDSK that came with your version of of DOS. Crossing versions can cause great damage to a disk.

Backing Up a Floppy Disk

Floppy disks wear out after several hundred spin hours. Well before then you should have made a copy of the disk to preserve the integrity of its contents. You can, of course FORMAT and then COPY *.* to accomplish this. There is a quicker way however:

DISKCOPY d1: d2:

If you do not give drive specifications, the utility will ask for them.

All information on the target disk will be destroyed, and DISKCOPY will format the target if it is found blank. Be careful, it's easy to destroy data by putting the disks in backwards!

Problem: Copy disk A: to B:. Issue the proper command.

Answer: C:\>DISKCOPY A: B:

Dealing with Files