ard(a)p850ug1.demon.co.uk (Tony Duell) wrote:
The 2350 is a USRT. And it just happens to be one that was used in some
hard sectored disk controllers - like the H17 card I have schematics of
here...
Hi
Controllers that used USRT's were almost always hard sectored.
Soft sectoring is done by having special clock/data marks that
are not normally valid for actual data. Picking these out requires
extra hardware that normal serial chips don't have. Softwarewise,
one could use soft sectored type disk ( not as soft sectored though ).
Most drives are actually quite stable in speed. They might vary
from drive to drive but on a specific drive, they are
reasonably
constant in speed. This means that one could use just the index
mark and a time delay to determine when to write or read a sector.
One might not be able to achieve the same density that was originally
used but it is still quite reasonable to do it this way.
Dwight