22 Dec
2006
22 Dec
'06
2:19 p.m.
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 always talk in terms of cylinders, even for a floppy. Well, 'always'
apart from calling the home signal on the inteface connector 'Track00'
and the write-current-reduction signal on a 8" drive 'Track Greater than
43'. Those names are so well-known (and given in just about every drive
service manual) that to call them 'Cyl00' and 'CG43' would just cause
confusion.
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)
One of the most confusion things relating to this was a manual that
claimed an IBM PC 360K disk had 80 tracks. It does (in 40 cylinders), but
it's still confusing.
Talking in terms of cylinders seems to be generally the norm with hard disks
though, and perhaps seems a bit more sensible - but remember that hard disk
manufacturers are the people who introduced decimal megabytes into common use :-)
Personally I prefer to talk in terms of 'surface number' rather than 'head
number', as a given surface could conceivably have more than one head in order
Well, if I had a drive with, say, 2 surfaces, 2 heads per surface, and
100 positions those heads could be moved to, I'd probably call it 100
cylinders, 4 heads, since logically it's the same as 4 surfaces with one
head per surface. Calling it 200 cylinders, 2 surfaces, while correct,
would seem to be as confusing as clalling it 400 tracks
-tony