Caution!
36OK-byte diskettes formatted on l.2M-byte high density, AT-style drives may not be reliable when used on some 360K-byte, XT-style drives. The /4 option switch is primarily intended to permit the use of less expensive diskettes with AT-compatible systems like this one.
If you need to have diskettes that can be safely read from and written to by both styles of computer, you should format the lower capacity diskettes on the XT-compatible system where they will be used.
Formatting a diskette allows you to use it by providing predetermined locations for certain files used by MS-DOS. Once formatted, the disk directory space is created, as well as additional areas reserved for use by MS-DOS. One of these areas is the File Allocation Table, or FAT. This part of the diskette contains a list of all of the files on the disk, and where they are physically stored on the diskette.
The other area is the system area. On your MS-DOS main system diskette, this area is occupied by the parts of MS-DOS that are copied into your computer’s memory during the startup routine. During the start-up procedure, the BIOS program, stored on the system motherboard, looks at this part of the diskette to retrieve the active parts of the disk operating
s y s t e m .
If these MS-DOS routines are not present in the system area of a diskette, the BIOS cannot startup the computer. This is what causes the error message:
DRIVE NOT READY ERROR
Insert BOOT diskette A:
Press any key when ready