So from what I read so far, I can use a hard sectored disk in place of a soft sectored disk? (or am I missing something?)
Hi
In many cases, you can format a hard sectored disk as a soft sectored
disk, as long as the drive doesn't expect the single hole to indicate
that the drive is ready( this is no true for many of the newer drives ).
The controller determines if you need hard or soft sectored. You can not
use a soft sectored disk with a hard sectored controller but as mentioned
before you can often use a hard sectored disk with a soft sectored controller.
On a hard sectored disk, there are many ways of keeping track of which
sector is currently under the head. As others mentioned, they may just
count sector holes from the index hole but in most cases, each sector has
a header before the data that includes the sector number and the track number.
In hard sectored, the controller knows to expect to see synch bytes, header
and the data following each of the sector holes.
In soft sectored, the controller watches for data/clock sequences that
would otherwise be illegal as data information. Usually there are several
types of these marks so that the controller can distiguish headers from
sector data or others, like deleted sector ( often used to mark a bad
sector ).
One of the others mentioned that soft sectored controllers keep track
of the sector by counting. This is not true, they actual just look at
each sector they come to and see if it matched the requested one
by reading the header. This is also true of most hard sectored although,
my Nicolet 1080 only puts only the track number as a header for the first sector
and counts holes for the next sector ( it uses 32 hole hard sectored disk
but partitions it into two large sectors, each 16 holes long ).
By determining the sector by reading the header, it is possible
to format the disk in such a way that the sectors are not in sequential
order. This is often done on slower machines that can not read
a second sector right after reading the first sector. It may have
to skip a sector before it is ready to read the next sector. If the
disk is formatted in sequential sector order, it would have to
wait an entire revolution before it could read the next sequential
sector. By skipping every other sector it could read the next
sector just as it was coming under the head. This is often called
interleaving. I do this on my H89 for the Heathkit basic. It can
make things load much faster.
Dwight