Browse Prior Art Database

Method and System for Split Count Loading in a No-ID(TM) Sector Servo Disk Drive

IP.com Disclosure Number: IPCOM000115760D
Original Publication Date: 1995-Jun-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 79K

Publishing Venue

IBM

Related People

Dobbek, J: AUTHOR [+3]

Abstract

The trend in disk drives and disk manager chips working in a sector servo environment is to store information as to where the next servo split will occur in the identification(ID) field prior to data. This split count information is used by the disk manager chip to break the data sector into sections positioned both before and after the servo burst.

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Method and System for Split Count Loading in a No-ID(TM) Sector Servo
Disk Drive

      The trend in disk drives and disk manager chips working in a
sector servo environment is to store information as to where the next
servo split will occur in the identification(ID) field prior to data.
This split count information is used by the disk manager chip to
break the data sector into sections positioned both before and after
the servo burst.

      In a No-ID(TM) disk drive no IDs are available to hold the
split information.  Several disk manager chips have the ability to
load split counts down into registers readable by writable control
store code.  These registers would also be loaded by the disk manager
when read from the ID field as described above.

      This system uses hardware to generate the split counts and load
the same registers loadable by a microprocessor.

      The method disclosed uses "Bus Master" loading.  The external
hardware takes control of the interface from the microprocessor and
drives the interface control signals and the data bus to load the
split count into the disk manager register.  This method "steals"
less than 1 microsecond from the microprocessor for each loading.

      The method does require a microprocessor bus like the Intel
80186/188 which allows other chips to take control.  Three primary
components involved and the interconnection signals between them are
shown in the Figure.  The "Microprocessor Selects Disk Manager"
signal (UP_CS_DM), is fed into the external hardware between the
microprocessor and the disk manager rather than being connected.  The
"Select Disk Manager" signal (CS_DM) generated by the No-Id(TM)
hardware, w...