FUJITSU MHD2032AT - Manual (Page 67)

Theory of Device Operation
4-18 C141-E050-02EN
4.7.2 Data-surface servo format
Figure 4.7 describes the physical layout of the servo frame. The three areas
indicated by (1) to (3) in Figure 4.7 are described below.
(1) Inner guard band
The head is in contact with the disk in this space when the spindle starts turning or
stops, and the rotational speed of the spindle can be controlled on this cylinder
area for head moving.
(2) Data area
This area is used as the user data area SA area.
(3) Outer guard band
This area is located at outer position of the user data area, and the rotational speed
of the spindle can be controlled on this cylinder area for head moving.
4.7.3 Servo frame format
As the servo information, the IDD uses the two-phase servo generated from the
gray code and servo A to D. This servo information is used for positioning
operation of radius direction and position detection of circumstance direction.
The servo frame consists of 6 blocks; write/read recovery, servo mark, gray code,
servo A to D, and PAD. Figure 4.8 shows the servo frame format.
Figure 4.8 Servo frame format