SuperDrives: "Bad Formatting" May Mean Disk Is High-Density




On a few occasions, when I have formatted an 800K floppy disk on a Macintosh
II or Macintosh SE, then tried to use it in a Macintosh IIx, Macintosh IIcx,
or Macintosh SE/30, I received a dialog box stating, "This is not a Macintosh
disk, do you want to format it?". Why?

This message, asking if you want to format a disk, occurs if the floppy disk
formatted in the 800K drive was a high-density disk. Check the disks
displaying this problem to see if they have a bonus hole -- an extra hole at
the top right corner of the disk. They are also marked as high-density disks.
There have been cases where high-density disks were put in packages with 800K
disks, so you might not even be aware that there are two different disks.

When high-density disks are put into an Apple SuperDrive (formerly Apple
FDHD), the drive sees the bonus hole and knows that it is a high-density
disk. It also sees that it was not formatted for 1.44MB and wants to do that.

The medium for the 800K disks is different than for the high-density disks,
and data is written differently to each. Because of this, we suggest that if
you have any high-density disks that have been formatted as 800K disks, copy
the information from the high-density disks onto 800K disks. The high-
density disks should then be re-formatted as 1.44MB disks.

For more information, read the three-part Tech Info Library article, "A Guide
to Using the AppleSuperDrive". Search under: "SuperDrive"



Published Date: Feb 18, 2012