AT&T 3B2/300 Technical Reference Manual page 546

- - - - - - - - - - - - - - - - - - - - - - - - - - - FUNCTIONAL DESCRIPTION
TO/FROM
SCSI
HOST
ADAPTER
CARD
r---------------------------, r----------,
I
DRIVE
MOTION
CONTROL
I
-
DATA
-
FORMATTING
CONTROL
:
I~
BUFFER
I
CONTROL BOARD
I
I
I
I
I
I
I
I
I
~
I
I
I
I
I
-,
I
I
I
WRITE
-
I
CONTROL
I
I
I
I
I
I
READ
~
CONTROL
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 3-92: 60-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 3-293