Browse Prior Art Database

Drive write process quick abort by Master Position Error Signal

IP.com Disclosure Number: IPCOM000014455D
Original Publication Date: 2001-Jan-01
Included in the Prior Art Database: 2003-Jun-19
Document File: 7 page(s) / 407K

Publishing Venue

IBM

Abstract

The servo signal is read from the servo pattern on the drive media. The head signal is transferred to Servo interface block by way of Arm Electronics (AE) and CHANNEL. Servo Assist makes servo calculation to get the head location with the data on the Servo interface. If the difference between target location and the current head location is over the criteria, media (drive) write process is aborted soon.

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Page 1 of 7

Drive write process quick abort by Master Position Error Signal

    The servo signal is read from the servo pattern on the
drive media. The head
signal is transferred to Servo interface block by way of
Arm Electronics (AE)
and CHANNEL. Servo Assist makes servo calculation to
get the head location
with the data on the Servo interface. If the
difference between target location
and the current head location is over the criteria,
media (drive) write process is
aborted soon.

Servo pattern

The exapmle flow of the process is shown below.

HDC/MPU

Servo locked

Restart

 Servo interface

MPU

Servo Assist Two adder Shifter Multiply & adder

Divider

Timer/SIO queue

256 byte SRAM

Drive Abort

Interrupt

Feedback

SIO

CHANNEL

AE

SPINDLE/VCM DRIVER

500ns

Pattern

Burst transfer A

SA process (Servo process)

Grey

Burst A

B

C

D

sync

DATA

B C D

900ns

Position abort

The rough track position (CYLID) is generated from the

1

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Page 2 of 7

Gray code. The detail
position (BUR_CYL and BUR_POS) are calculated from the CYLID
and the 4 burst
data (A, B, C, D) as shown below. The 4 burst data are
transferred from the
CHANNEL to Servo interface. The Position Error Signal
(PES) is used for the
calculation. The Master PES (MPES) is calculated from
BURST-A & BURST-B
and Slave PES (SPES) is from BURST-C & BURST-D.

2

Page 3 of 7

Position Error Signal (PES) decoding for location generation

Gray code : CYLID

BURST-A

B

C

CYLINDER increaseREAD HEAD

FF

80

01

100

ODD EVEN ODD EVEN

D

C - D

C + D

A - B

A + B

01 =< H =< 7F

 Linear part of MPES or SPES is used for BUR_POS generation to remove magnetic distortion effect.

000

BUR_POS equation for the range left

SPES-80

-MPES

-MPES

-SPES+80

-SPES-80

MPES

MPES

SPES+80

3

ODD EVEN ODD EVEN

SPES = ----- x H + 80

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Page 4 of 7

The aborting condition is

| BUR_CYL, BUR_POS - TAR_CYL, TAR_POS | > APEC

APEC is the abort criteria. It takes about 900ns for SA to
make drive abort
process.

   Generally, the earlier drive abort process is required
because of increasing
media data rate. The target of this invention is to supply
the quick drive aborting
method before media data process start.

The write head is on the center of the track (BUR_POS =
80) when drive write
process is undergoing. Then the aborting process is
possible only by MPES and
the calculation can be start from the BURST-B r...