From: awanderin@gmail.com   
      
   engrav  writes:   
      
   > Hi   
   > Have Powerbook 180, Powerbook G3 and Apple //e with external 3.5 hard   
   drive.  I can format   
   > a 3.5 disk ProDOS on all 3 machines.  But...   
   >   
   > The disks are not interchangeable.  That is, for example, the disk formatted   
   on the G3   
   > cannot be read by the Apple //e.  Etc.   
   >   
   > Why is this?  I did something wrong?  I am missing something?   
      
   Are the 3.5" disks in the Powerbooks 1.44M disks?  That is, high-density   
   (HD) disks?  Those are formatted using the MFM encoding while the 800K   
   Apple disks are formatted with GCR encoding, and also the 800K drives   
   change speed depending upon which track is being accessed.   
      
   Unless your Apple IIe has the 3.5" superdrive disk controller card that   
   supports the Apple 3.5 FDHD drive, and you have a FDHD drive connected,   
   you cannot read the 1.44MB floppies on your Apple IIe.   
      
   Simple test.  On your Powerbooks, format the disk and see how much free   
   space it reports on the disk.  If it's more than 1.3 MB, it's a FDHD.   
      
   Try formatting on the Apple IIe.  What is the free space there?  If it's   
   just under 800k, it's using the GCR format encoding, and your drive   
   probably only supports double-density (800k GCR).   
      
   --   
   --   
   Jerry    awanderin at gmail dot com   
      
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