Resolution
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This issue has been fixed with System 7.5.3 Revision 2. This software can be found on Apple Computer's online software update sites. If you do have not access to an online service please refer to Tech Information Library article, "Macintosh System 7.5.3 Revision 2: FAQ." If you do not have System 7.5.3 Revision 2, follow the workaround provided below.
Original Issue
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If a floppy disk is formatted as DOS format on a PowerBook 500 series computer with the PPC Upgrade, DOS/Windows computers will not be able to recognize the disk. Other Macintosh computers, however, recognize the disk as a DOS disk.
If a floppy disk is formatted on a DOS/Windows computer and then inserted into a PowerBook 500 series computer with the PPC Upgrade, the PowerBook will recognize it as a DOS floppy. However, if the disk is then removed from the PowerBook and taken back to a DOS/Windows system, that disk will not recognized by the DOS/Windows computer.
Explanation
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There was an inadvertent change made to the floppy driver of the PowerPC-upgraded PowerBook 500 series computers. This change makes a DOS disk unreadable by DOS/Windows computers if the PowerPC-upgraded PowerBook 500 series computer formats the disk or is the first Macintosh computer to read the disk after it has been formatted on a DOS/Windows computer.
Workaround
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If you cannot immediately install, the System 7.5.3 Revision 2 there is a workaround. You need to either format the disk as DOS on a Mac other than the PowerBook 500 series computer with the PPC Upgrade or make sure a Mac other than the PowerBook 500 series computer with the PPC Upgrade is the first to read the disk after it has been formatted on a DOS/Windows system. After another Macintosh has read the disk and written the resource fork (which is necessary in order for the Macintosh file system to recognize the disk), all other Macintosh computers (including the PowerBook 500 series computer with the PPC Upgrade) and DOS/Windows systems should be able to read the disk.
These articles can help you locate the software update mentioned here:
* "Where To Find Apple Software Updates" -- Lists online services for free Apple software updates.
* "Obtaining Apple Product Support in the USA" -- Lists 800 numbers and online services for software updates, Apple support information, and a subset of the Apple Tech Info Library.
Article Change History:
18 Jun 1996 - Reworded for clarity.
15 Jun 1996 - Added System 7.5.3 Revision 2 fix.