Table of Contents
Advertisement
To keep the air circulating within the drive free of particles, the
drives are assembled in a Class 100 clean room environment, and then
sealed with a metal cover.
During the life of the drive, the rotating
disks pump the enclosed air through an internal 0.3 micron recircula-
tion filter, as shown in Figure 2-2.
Another 0.3 micron filter, not
shown, allows outside air into the sealed area of the drive to
equalize internal and external pressures.
2.2
Drive Electronics
2.2.1
Disk Format
Q200 Series drives employ 823 user tracks (refer to Figure 2-3), while
seven tracks are reserved for disk drive system uses -- such as defect
lists, serial number ID and factory test data.
Each data track con-
tains thirty-two sectors and thirty-two servo wedges.
Each user data
area consists of a preamble and synchronization area, 512 bytes of
data, and 12 bytes of ECC.
A short postamble flushes the ECC buffers
in DICEY.
within the servo wedges are the servo tracks--three times as many as
the data tracks--written in staggered sequence so they don't overlap
on the disk.
In a wedge, a servo track starts with a unique qual area
that identifies the area as a wedge, and ends with a servo burst.
As
with the data areas, each burst begins with a preamble and synchroni-
zation area.
In the bursts, this is followed by the servo track num-
ber, the head number (bursts A and C) or the sector number (bursts B
and D), a checksum that allows error detection, and a short postamble.
At 3662 rpm, a complete sector, including wedge and 512-byte data
area, passes under its head in 512 microseconds.
The data itself
passes under the head in about 410 microseconds, giving a maximum user
data transfer rate of about 10 M bits/sec, i.e., 1.25 MBytes/sec.
2.2.2
Simplified Explanation--Block Diagram
This section summarizes the operation of the drive, as an introduction
to the more detailed sections that follow.
Refer to Figure 2-4, a
simplified block diagram of the system.
2-4
Advertisement
Table of Contents
