[Coco] 3.5" Drive Variable in the NitrOS-9 Module Header

Kip Koon computerdoc at sc.rr.com
Sat Jan 26 22:11:06 EST 2013


NitrOS-9 Developers,

I have been giving some serious thought to the recent discussions about when
to use a track density of 48 tpi or 96 tpi.  Here's my thoughts on the
matter.  Create a new bit in the Drive Descriptor which is called '3.5"
Drive Track Density' and this is how it would work.  When this bit is set to
0 (zero) the other track density bit would be active.  When set to 1 (one),
the other track density bit's effects are deactivated and the new track
density becomes 135 tpi.  We could also implement a bit called "Quad Data
Density"  to take advantage of the 3.5" drive's highest data density
capability and finally reach the full capacity of a 1.44 floppy disk drive
and it could work in a similar fashion.  When the bit for Quad Data Density
is 0 (zero), the other data density bit is active, and when the Quad Data
Density bit is 1 (one) the other data density bit is deactivated and the
data is encoded onto the floppy disk's surface using the 3.5" drive's Quad
Data Density capabilities.  Of course all disk drive drivers would have to
be updated to implement the change in the Drive descriptor giving the
correct commands to the 3.5" drive when appropriate.  If there is space for
these two new bits in the current Drive Descriptor Definition, there may be
the possibility that only floppy drive drivers would need to be updated due
to the definition that if both new bits were 0 (zero) their older
counterpart bits would remain active and all should be well.  So guys, what
do you think of my brain storming session?  Do you all think that this may
be possible?  So far in my thoughts, it sounds very doable.  Thanks for
considering my suggestion.

Kip

 




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