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PROGRAMMING NOTE: Any command issued to a 2265 that is
performing a 2265-to-Printer operation causes the print operation
to be terminated immediately. The print mechanism will not be
positioned to a new line. The keyboard of the 2265 is restored
upon completion of the command.
Tab Feature Operation
Tab operation on the 2265 Display Station is performed in
a manner similar to the tab operation on a conventional
typewriter. A colon (:), displayed on the 2265 screen,
serves the same purpose as a typewriter tab stop. Colons
are entered in the desired locations on the display either
by depressing the colon key on the 2265 or as part of
transmitted text from the CPU.
When the TAB key on the 2265 keyboard is depressed,
the keyboard is locked, and a search for a colon is initiated.
Each character position is checked, including those to the
right of an NL symbol. When the end of a row is reached,
'the search continues at the beginning of the next row of
characters. Upon detection of a colon, the cursor is posi-
tioned to the character location immediately following the
colon. If the colon search is continued to the end of the
screen and no colon is found, the cursor is positioned to
the first character location in the upper left of the screen.
In either
eve~t,
the tab operation is ended, and the key-
board is unlocked. The next characters entered into the
system, either from the keyboard or under program con-
trol from the central processor, will be displayed at the
cursor's new location.
The colon search begins at the cursor's present position
in display systems using the standard nondestructive cur-
sor. Therefore, if the nondestructive cursor and a colon
are both occupying the same character location when the
TAB key is depressed, the cursor will move only one posi-
tion. In a tab operation using the nondestructive cursor,
there is no change in the display other than the reposition-
ing of the cursor.
On the other hand, the colon search begins at the loca-
tion immediately following the cursor in display systems
equipped with the Destructive Cursor Feature. Also, any
character being displayed in the position immediately fol-
lowing the detected colon will be replaced by the destruc-
tive cursor.
Note that the tab operation can be initiated from the
2265 keyboard only, No provision is made for a remote
tab operation by means of any USASCII-8 or unique con-
trol character.
Display System Test Procedure (Wrap Test)
The TEST key, located on the Display Station keyboard,
enables the operator to test the operation of the display
system without affecting other units attached to the com-
munications channel. This test may be performed if a
communications problem is experienced with the central
processor. The test (sometimes referred to as a "wrap"
test) may be helpful in localizing the problem to: (I) the
2845; (2) the host system (including the I/O channel,
2701, and associated data set); or (3) the communications
facilities. Depressing the TEST key effectively disconnects
the display system from the data set and communications
channel. In this off-line condition, no message can be
transmitted to or received from the central computer, and
depressing the 2265 keyboard keys has no effect on the
communications network. By observing the test operation
(as described below), the operator may make a judgment
as to the operating condition of the display system.
The test is performed as follows:
1. Depress the TEST key.
This switches the 2265/2845 off-line, erases the entire
screen, and places an SOM and cursor in character posi-
tions 1 and 2, respectively. A Write Addressed DS oper-
ation is internally generated by the 2845, causing the
character sequence %6G
~to
be written once, beginning
at the cursor location (position 2 of line 1). Following
this action, the character sequence %6GW is written re-
peatedly in consecutive character positions beginning in
the first character position of line 2. This operation
simulates receiving a message from the central processor.
2. Depress the RESET key.
This action, which causes the write operation to end,
must be taken in time to prevent the SOM symbol from
being overwritten by the %6GW character sequence.
Note: If the RESET key is not depressed in time, and the
SOM symbol is overwritten, the test must be restarted. To
restart, depress the following keys in this order: RESET,
ENTER, TEST, RESET. Now start at step 1.
3. Depress the ENTER key.
This action causes the EOM symbol to be written follow-
ing the last character of the four-character sequence.
4. Depress the TEST key.
This action causes the Read operation to occur. This
operation may be observed due to the nondestructive
cursor advancing repeatedly from the SOM symbol to
the EOM symbol. Cursor movement is not visible when
the 2845 is equipped with the Destructive Cursor Fea-
ture.
5. Depress the RESET key.
This action terminates the simulated polling operation.
It also restores the 2845 to an "on-line" condition; i.e.,
reconnects the 2845 to the data set and thus to the
communications channel.
I
6. Depress the ERASE DPL Y key.
This action clears the screen of the test display. If the
test is performed satisfactorily, normal communications
may be resumed.
Note: Once step 1 of the wrap test procedure has been per-
formed, the remainder of the sequence (through step 5)
Introduction
23
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