Disk II Family's Phase

["Bryan Parkoff" <BParkoff@satx.rr.com>]

    It seems to be interesting that standard Disk Drive only uses Phase0
that is turned on for reading and writing, but all Phase0, Phase1, Phase2,
and Phase3 are always turned off.  I wonder why Phase1, Phase2, and Phase 3
are not used for turning on.
    Please explain what Phase do.  I understand that it is used for stepping
arm to move from outer toward inner.

    Is it true that stepping arm always move from outer toward inner by
reading SELECTIVE track and sector?  Does it mean that software has NO WAY
TO TELL hardware to LOCATE track and sector.  The hardware's job is to
retrieve each bit by reading from outer toward inner.  In fact is that it is
the software's job to SEARCH track and sector before track and sector are
compared to match user's desire track and sector BEFORE 256 bytes in a
sector dump into memory.
    Does it make sense?

--
Yours Truly,

Bryan Parkoff
BParkoff@satx.rr.com