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1.15
ORGANIZATION OF THE DISK DRIVE
All electrical subassemblies in the disk drive are constructed with leads that terminate in 4- to 5-pin connectors,
enabling the individual assemblies to be removed.
The magnetic heads are connected to the PCBA via cables that terminate in 5-pin female connectors and their
associated male sockets, which are located in close proximity to the Read/Write data electronics.
Interface signals and power are ;Jrovided via connectors at the rear of the disk drive.
1.16
COMPONENTS OF THE DISK DRIVE
The disk drive consists of seven (7) functional groups
:
1.
Index Pulse Shaper
2.
Write Protect Sensor
.
3.
Track 00 Sensor
4.
Spindle Drive Control
5.
Carriage Position Control
6.
Write/Erase Control
7.
Read Amplifier and Digitizer
Figure 1-2 is a functional block diagram of the disk drive. It should be referred to in conjunction with the following
sections. The data in the ensuing figures is primarily represented in simplified form.
1.16.1
Index Pulse
An index pulse is provided to the user system via the Index Pulse interface
line.
The index circuitry consists of an
Index LED, an Index Photo
Transistor,
and a Pulse Shaping
Network.
As the index hole in the disk passes the In-
dex LED/Photo Transistor
combination,
light from the LED strikes the Index Photo Transistor, causing it to con-
duct. The signal from the Index Photo Transistor is passed to the Pulse Shaping Network, which produces a pulse
for each hole detected
.
This pulse is presented to the user on the Index Pulse Interface line.
1.16.2
Write Protect
A Write Protect signal is provided to the user's system via the Write Protect interface line. The Write Protect cir-
cuitry consists of a Write Protect sensor and circuitry that routes the signal that is produced.
When a write protected diskette is inserted in the disk
drive,
the sensor is activated and the logic disables the write
electronics and supplies the status signal to the interface.
1.16.3
Track 00 Switch
The level on the Track 00 interface line is a function of the position of the magnetic head assembly. When the
head is positioned at Track 00 and the stepper
motor
is at the home position, a true (low) level signal is generated
at the interface.
1.16.4
Spindle Drive System
The Spindle Drive system consists of a spindle assembly driven through a drive belt by a DC motor/tachometer
combination
.
1-7
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