Re: Stupid Questions 102

[a2pro.gelamp@genie.com]

bpvh@primenet.com (Bradley P. Von Haden) writes:


>dturner@brando.ece.utexas.edu wrote:

>Normal Apple IIgs disk drives can not read MS-DOS disks - something
>to do with the way information is written onto the disk that is
>hardware (?) incompatible.

yes, it is hardware incompatible.  The difference is that Apple 3.5" disk
drives (double density) use a variable-speed motor to keep the linear
velocity of the surface under the head constant, rather than faster on outer
tracks than inner tracks.  By doing this, more information can be stored on
e outer tracks.  (This is why Apple drives store 800k, instead of only 720k
like IBM drives, which use a constant angular velocity resulting in a higher
linear velocity at the outer edge of the disk.)

The Apple SuperDrive can run at constant speed or variable speed, so it can
read either type of disk.
--
         Tim Buchheim           |  Apple II user and programmer
         ~~~~~~~~~~~~           |  Editor, GEnieLamp A2Pro
   tim.b@tiberius.st.hmc.edu    |  Asst. Sysop, A2Pro RT on GEnie
   tim.b@genie.com              |  
   a2pro.gelamp@genie.com       |  "Whatever" -- K.S.  :)