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4.3.6
Carriage Return and Line Feed Operation (See Time Chart (2),
Fig. 4-9.)
After one line has beeD printed, the I/O RAM reverses the sequence
of phase pulses from PB4 - PB7.
This moves the carriage in reverse
At the same time outputs PBO to PB3 are enabled to the line feed
pulse motor.
These pulses (LO-TRU) are applied to 04, Q5, RM2, and
09 (or 08) to the line feed pulse motor.
This motor has 24 V d.c.
applied at all times via connector CN3-5 and 6.
The line feed puls
motor advances one line (24 steps if 6 LPI, or 18 steps if 8 LPI).
The line feed pulse motor is similar in operation as the space pulsl
motor, however, only a forward direction is used.
The space pulse motor continues in reverse, until HOME is detected.
\.vhen this happens, the photo - LED cell applies a HI, via CN7-3,
to interrupt the
~CPU
at 02-1 (TO).
This causes a branch in the
~CPU
program to the routine which will clear BUSY and output ACK
to the interface.
The printer is ready for the next data input.
4.3.7
Paper End and Print Switch Operation
A paper out condition is sensed by the paper roll holder via
connector CN2, or by the paper out switch on the unit, via CNI.
Either switch, when paper runs out, will apply a LO to 05-13.
This produces FLT (LO) to the interface CN6-32.
Also Q5-12
goes HI, this signal is PE (Paper End) on CN6-l2.
When the PRINT SWITCH is "ON", a HI is felt on 07-4, through
R14, which is connected to +5 V d.c. 07-5 monitors the paper
out condition, and will be HI if paper is not out.
07-6 will
go LO when Print Switch is on, HI if the Print Switch is off,
or paper out occurs.
This HI signal is applied to the
~CPU
pin 39 (Tl), to inform the
~CPU
of a fault condition.
The
~CPU
will direct 01 to output a BUSY signal after completing one line
of print, therefore disabling input data until the fault
condition is cleared.
4.3.8
Graphic Printing Operation
As shown in Fig. 4-11, a domain is divided into 6 minimum units
by character and line spacing pitches, and these units are combined
to form a graphic character.
bl
b3
b5
__ ()roehic
___J
(where b2. b3 and
b6 are
all ..
I' s • ).
/
b2
b4
b6
-
..
I
I
A
I
!
Character
Fig. 4-11
Graphic Printing
'tn
N
-
Ci
0
I'-
I£'
0
~_o.06i"
or
o~oo:-'
49
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