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Power necessary to drive the sprocket-feed paper tractors controlling
paper movement, is transmitted from the main motor through an O-ring belt
to the form feed mechanism, where it is then transferred via the paper drive
shaft to the paper tractors. The form feed mechanism consists of a form feed
or release clutch, a line feed solenoid with slide unit, and a gear train
mechanically linking the main motor to the paper feed tractors.
To initiate a single line feed, the line feed solenoid is energized
15 milliseconds. Upon completion of the line feed command, a 60-90 millisecond
delayed line feed interval is generated. This allows the clutch pawl and
clutch mechanism to return home before another line feed is allowed.
Vertical forms movement is accomplished by applying a DC level to
the paper feed solenoid. In the standard 306 printer, this paper movement
continues until it is either terminated by the reception of a delete code
(octal 177) or an INPUT PRIME signal at the interface connector, or a paper
time-out condition. However, if the optional Vertical Format Unit (VFU) is
used, the paper movement is terminated when a hole is detected in the
appropriate channel of the vertical format paper tape.
As paper moves in the printer, each line advance causes a line count
switch located in the form feed mechanism to open and close. The two wires
from this switch go to the interface connector via the logic card. As a
result, a line count level from the input device is switched on and off by
the printer for each line advance.
If the 306 contains no optional VFU,
the user's software can control vertical formatting by counting these line
count pulses and terminating the paper movement operation when appropriate.
When the printer runs out of paper, a sensing switch activates a
two-second audible tone in a speaker (option) located at the rear. The
printer also stops printing and lights the PAPER EMPTY light on the control
panel.
1.3.3
SPECIAL FUNCTIONS
In addition to the printable characters shown in Appendix B, and
the carriage return, line feed, form feed, and vertical tab codes previously
described, the printer also recognizes the following special control codes.
Delete (Octal 177) - Primes the printer electronics and clears the
buffer.
Bell (Octal 007) - With Bell option only - Generates a two-second
audible tone in the speaker at the front of the printer.
Select (Octal 021) - Allows printer to receive data, same as
activating
SELECT
switch.
1-5
same
Rev. 0
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