Apple Macintosh Performa 6400 Series - Manual (Page 84)

Your Macintosh can’t read a floppy disk.
If you see a message that a floppy disk is unreadable, try one of the following:
m If the disk has never been used, you may simply need to initialize it—that
is, prepare it for use. For instructions, see the “Disks” topic of Macintosh
Guide, available in the Guide (h) menu.
m The disk may be damaged. See “Repairing a Damaged Disk” later in this
chapter for information on testing and repairing disks.
m The disk may have been formatted for use on another kind of computer.
You may be able to use a program that lets you work with such disks on
your Macintosh.
If you are trying unsuccessfully to use a DOS floppy disk, consider the
following:
m When formatting floppy disks on a DOS computer for use in a Macintosh,
you need to format standard double-sided disks as 720K disks and high-
density disks as 1440K disks. Double-sided disks formatted in 1440K
format and high-density disks formatted in 720K format may not work in
a Macintosh.
If you think your DOS floppy disk might have a format that doesn’t work
in a Macintosh, use a DOS computer to copy the contents of the disk onto
a properly formatted disk.
m Make sure the PC Exchange control panel is in the Control Panels folder
(in the Apple [K] menu) and that it is enabled. To enable PC Exchange,
open the Extensions Manager control panel and click the PC Exchange
item (under the Control Panels heading) to make a checkmark appear.
Then restart your computer.
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