Cylinders versus tracks...

Dave Dunfield dave06a at dunfield.com
Fri Dec 22 09:46:05 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?
> 
> People often seem to talk about floppy drives in terms of tracks, heads and 
> sectors (e.g. for an 80 cylinder floppy with two sides they'll still talk in 
> terms of tracks 1-80 in conjunction with a side number, even though the media 
> has 160 tracks in total)

The problem is that "Tracks" is ambiguous - it could be "track number the start
of the surface" or "track number from the start of the entire media" both uses of the
term have become common enough that the meaning has to be explicitly stated.

My vote is for Cylinders to refer to the position over any surface (ie: from
Cylinder 0 - funny - many referefnces refer to this as Track-0 even if they
use the Cylinders convention otherwise), and for Tracks to refer to the position
from the beginning of the media (entire disk) - But I know I've used Tracks
in both ways - best to explicitly state which convention you are using.

btw - with floppies, it can be worse - NorthStar floppies are logically treated
as a single range of 35, 40, 80 or 160 tracks (depending on the type of drive)
however when you reach the innermost Track/Cylinder of Side-0, the next
logical track is the innermost track/cylinder of Side-1 - in other words, it steps
in for increasing track numbers when they exist on Side-0 and out for
increasing track numbers when they exist on Side-1 - So absolute track and
sector numbers (absolute from start of media) will be different than you might
expect if you are used to a system which advances C/H/S though it's
logical progression. This is yet another ambiguity with "Tracks".

--
dave06a (at)    Dave Dunfield
dunfield (dot)  Firmware development services & tools: www.dunfield.com
com             Collector of vintage computing equipment:
                http://www.classiccmp.org/dunfield/index.html



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