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1.2.5
Microprocessor-Controlled Head positioning
The head positioning (access) mechanism consists of a step
motor, linked to the carriage by a tensioned steel belt.
This arrangement provides fast and accurate access.
The
step motor
is controlled by a microprocessor,
increasing
head posi tioning reliabili ty.
Each pulse command rotates
the step motor shaft 1.8 degrees, which moves a head/car-
riage 1/2 track on the flexible disk.
1.2.6
Microprocessor-Controlled Head Loading
When the disk drive logic circuit receives a head load in-
structiori, it lowers the heads onto the flexible disk sur-
faces.
Head loading force is controlled by a solenoid.
A
microprocessor-controlled special cam governs head loading,
reducing damage to the flexible disk surface, thereby in-
creasing flexible disk operating life and data integrity.
1.2.7
Display LEOs
Two LEOs on the front panel provide a visual display of the
ready and busy states of the disk drive.
1.2.8
Door Lock Solenoid
The door lock solenoid makes it impossible to remove a disk
during certain drive operations,
thereby preventing data
loss or physical damage to the flexible disk.
1.2.9
Interface
Signal and data lines interface with the host controller is
by a 50-pin edge card connector.
The 21 active lines (plus
grounds) are all operated at TTL levels.
The Variable Fre-
quency Oscillator (VFO) option requires another three lines.
1.2.10
Diagnostics
The disk drive diagnostics consist of movable printed cir-
cui t board (PCB) plugs that can be used to establish test
conditions.
1-4
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