IBM 5150

If You Have One Drive
1 Make sure DOS is ready and A> is displayed.
2 Insert your DOS Diskette into the drive if it is not
already there.
3 Type this:
format b:
and press the Enter key.
4 This message is displayed:
Insert new diskette for drive B:
and strike any key when ready
BE CAREFUL NOT TO TOUCH THE KEYBOARD
ACCIDENT ALLY UNTIL
THE DISKETTES HAVE
BEEN SWITCHED.
5 Remove the DOS Diskette and keep it handy.
6 Insert the back-up diskette into the drive.
7 Press a key to tell DOS that the diskettes have been
changed.
DOS 3-24