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· depressing a different character key (to replace the charac-
ter). Rapid positioning of the cursor by the operator is
also provided. By depressing the proper key, the cursor may
be moved up, down, left, or right.
The functions of the commands and keyboard keys are
described in detail later in this publication.
OPERATION WITH 1053 PRINTER
When a 1053 Printer is attached to the Display Control,
the data displayed on a 2265 screen can be printed by
depressing the PRINT key on the 2265 keyboard. All data
from the first displayable character position of the screen
up to the character position occupied by the cursor (except
for those characters to the right of and on the same line as
the NL character) are transferred to the Printer. Detection
of the EOM symbol ends the print operation immediately
after the EOM symbol is printed. Because the EOM symbol
may be displayed to the right of an NL symbol, all charac-
ter positions to the right of an NL symbol are searched for
an EOM symbol even through the characters displayed in
these positions are not printed. (The EOM symbol itself
is printed.)
If an internal parity error occurs within the 2845 after
a keyboard print operation is initiated and before the
operation is terminated, a Check symbol ( ' ) is printed as
the last character of the printed text. The Check symbol
notifies the operator that an internal parity error has been
detected, but does not identify the character(s) involved.
The parity error may have occurred in either the display
buffer or the printer buffer. In any case, all characters are
printed as they exist in the display buffer.
Remotely, by means of a Write Printer command, the
central processor may send a message of up to 240
characters via the 2845 to the 1053 Model 4 Printer. The
entire message is received and stored in the printer buffer
of the 2845 before it is transferred to the Printer. If an
error is detected during message transmission, transfer to
the Printer is inhibited and the entire message must be
retransmitted. If, however, no errors are detected in
transmission, receipt of the final message character initiates
transfer of the message to the Printer and printing com-
mences.
As in the keyboard PRINT key operation, detection of
an internal parity error, either in the printer buffer or
display buffer of the 2848, causes a Check symbol to be
printed as the last character of the printed message. The
Check character simply indicates that an error has been
detected within the 2845 but does not identify the
character( s) involved.
A message of up to 240 characters may be sent by -the
central processor to the Printer via the 2845. A Printer
message of greater length may be sent to the Display
Station, with the operator instructed (as part of the
message) to execute a keyboard Print operation. Or,
th~
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message may be sent in individual Write Printer trans-
missions of 240 characters or less directly to the Printer.
During transmission from the central processor to the
Printer, data displayed on the display screen is not affected.
The 1053 Piinter, when controlled by the 2845, is
equipped with a special print element that permits printing
of the SOM, EOM, and Check symbols. Therefore, all
characters are printed as they exist in the printer buffer.
However, the NL symbol is not printed; rather, it causes
a carriage return/line feed (CR/LF) operation.
2265 DISPLAY STATION OPERATOR CON'FROLS
AND INDICATORS
Operator controls on the 2265 Display Station (not
including those located on the keyboard) are a POWER
ON switch/indicator, a POWER OFF switch, and a
Brightness control. (A single POWER ON/OFF switch is
the only control on the 2845 Display Control accessible
to the operator.)
The POWER ON switch/indicator is located on the front
right side of the 2265. Upon depression of this switch/
indicator, all voltages required for operation are supplied
to the 2265 and 2845 provided the 2845 POWER ON/OFF
switch is set to ON. When all power is on in both units,
the 2265 POWER ON switch/indicator lights. Voltages
necessary for operation are turned off in both units when
either the 2265 POWER OFF switch (located immediately
below the POWER ON switch/indicator) is depressed or
when the 2845 POWER ON/OFF switch is flipped to OFF.
(A 49V source, located in the 2845, is energized and
supplies 49V to the 2265 when the 2845 POWER ON/OFF
switch is ON regardless of the condition of the 2265.
power switches. However, other voltages, off at this time,
are required to make both units operational.)
The Brightness control is located immediately above
the POWER ON switch/indicator on the 2265. Rotating
the Brightness control knob clockwise increases the
brightness of the characters displayed on the screen, thus
enabling the operator to adjust the brightness to a com-
fortable viewing level.
Two indicators are located on the 2265 keyboard. The
DATA SET READY indicator notifies the Display Station
operator that the attached data sethas power on and is
I
ready to function. The ENTER PENDING indicator
informs the operator that an Enter operation is pending.
I
While the ENTER PENDING indicator is lit, the keyboard
is locked. The ENTER PENDING indicator lights when the
ENTER key is depressed and is extinguished when one of
the following occurs:
1. Polling of the Display Station is successfully terminated.
2. The RESET key is depressed before 2845 recognition
of a specific or general poll.
13. Any other command (except Read Addressed Full DS
Buffer) precedes the polling operation.
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