AT&T 3B2/300 Technical Reference Manual page 550

- - - - - - - - - - - - - - - - - - - - - - - - - - - FUNCTIONAL DESCRIPTION
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TO/FROM
SCSI
HOST
ADAPTER
CARD
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r---------------------------,
r----------,
I
I
I
-
I
DRIVE
I
-
MOTION
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CONTROL
I
DATA
WRITE
FORMATTING
CONTROL
CONTROL
i
BUFFER
I
READ
CONTROL
CONTROL BOARD
I I
I I
I
I
I I
I I
I I
I I
~
I
I
I
I
_.
I
I
I
I
-
I
I
I
I
I
I
I
~
I I
-
I I
I I
I I
I I
I
I
I
I
SENSOR
GROUP
HEAD
STEPPER
CAPSTAN
DRIVE
MOTOR
READ/
WRITE
HEAD
DRIVE CHASSIS
L---------------------------~ L----------~
Figure 3-94: 120-Megabyte Cartridge Tape Drive - Functional Block Diagram
Tape Drive
Tape motion is via a capstan driven by a 8-pole, 3-phase, brushless DC motor. The motor speed is
controlled by an onboard microprocessor using pulse-width modulated signals. Tape speed is 90 inches
per second.
Read/write head positioning is done by a stepper motor controlled by the onboard CPU in
response to the interface signals. These signals are converted into discrete mechanical movements
referred to as steps. The steps are changed in a logical sequence to move the stepper motor the desired
number of steps for the required stream selected.
FUNCTIONAL DESCRIPTION 3-297