Hard-sectored 5.25" disks

From: Dwight Elvey <elvey_at_hal.com>
Date: Mon Mar 22 14:43:44 1999

ard_at_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
Received on Mon Mar 22 1999 - 14:43:44 GMT