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DIDS-402-2MlO
Para 3-6.2/3-6. 3
When a complete character code is in the character entry register prior
to being shifted into the delay line. it is strobed simultaneousl y into the six-
character readout flip-flops and held for the duration of character time (figure
3 -10).
The output of the character readout circuit is fed to the monoscope
deflection amplifier where it is converted from digital information to analog
information to position the monos cope beam so that it sweeps acrOSS the target
character.
3-6.3 Display Editing.
The display editing circuits consist of the specific editing
functions that take place before and after the character entry register functions.
The message from the delay line is fed into the display logic circuits
(located on board Al3). through the shift register. and then back to the display
logic circuits prior to re-entering the delay line (figure 3-11).
Access to the
message is possible both before and after it goes through the shift register.
The message is processed in the display logic circuits which can perform the
following functions:
Shift cursor to the left
Shift cursor to the right
Erase a line
Erase a message
Advance line
Back line
Return cursor to beginning of frame
Insert
Delete
Cycle
The delay line stores the message minus one character .. There is always
one character in the shift register preparing to enter the display logic and then
the delay line.
In order to shift the cursor to the right. the cursor must be de-
layed in time by one character.
To accomplish this shift. the cursor is removed from its slot when it ap-
pears at the end of the shift register and is inserted at the beginning of the shift
register in the cursor slot of the next character (figures 3-11 and 3':"12).
A
similar process is used to shift the cursor to the left.
The cursor must be
made to occ ur one character time earlier.
To do this. the cursor is removed
from its slot after leaving the delay line. and inserted into the curSor slot of
the character in the shift register.
In effect. the cursor bypasses the trip
through the shift register.
It
is then added to the preceding character. with
the result that the cursor shifts to the left.
3-17
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