"David Wilson"  wrote in message 
news:78e4f06d-aae1-46d7-a777-08e542bc16b5{at}v18g2000pro.googlegroups.com...
On Feb 5, 11:56 am, "Charlie"  wrote:
> Its just that nothing I've ever read from
> Apple gives any indication that the rotational speed of the drive can be
> controlled from outside the drive.

>------------------------------------------
The original 400KB Mac 3.5" drives had their speed controlled by the
Macintosh. AFAIK, the 800KB drives ignore the speed signal on pin 10
of the 19 pin connector. On the Apple IIc and IIgs this pin is used as
the Write Protect signal.

See http://support.apple.com/kb/TA48050?viewlocale=en_US for pinout
and signal descriptions.
>------------------------------------------

That's interesting.  I never thought to check Mac info.  It's also a little 
confusing (at least to me :-)  How can the same pin be used for two 
different functions depending on which computer is used?  Can't the Mac 
detect a write protected disk?

Charlie
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