Cylinders versus tracks...
Brian L. Stuart
blstuart at bellsouth.net
Fri Dec 22 09:40:20 CST 2006
> Out of interest, which is the correct terminology when defining a single point
> on a disk's surface - is it better to talk in terms of cylinders, or tracks?
I generally teach it this way. A track is the path traced by a single head
during a rotation of the spindle. A cylinder is the set of tracks traced
by all the heads for a single position of the arm. Thus specifying the
cylinder number specifies the position of the arm. Specifying the
head number selects the desired track from the set in the cylinder.
> cylinder/surface/sector or track/surface/sector. It's all just semantics, but
Track/surface is actually redundant since the combination of cylinder and
head uniquely identifies a track. In other words, the track number implies
As to the usage in the floppy world, I'd guess that it started with the old
single-sided floppies. For them, a cylinder and a track were the same
thing. Then for double-sided floppies, people tended to talk in terms
of a track number on a side and didn't think in terms of cylinders at
all. But on multiplatter disks, the concept of a cylinder becomes a lot
more meaningful. Regardless of how many surfaces we have, it is
the difference between our current cylinder number and the desired
one that dominates the access time.
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