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DIDS-402 -2AM13
e.
A step-right cursor control function is initiated when the cursor
is associated with the last character of the line
f.
The END key is depressed (One-step Transmit option)
To perform an advance-line function, the cursor is located in memory by
sensing its presence in the cursor-located flip-flop of the CE register.
When
the cursor is found, it is erased before re-entering the delay line.
The cursor is
then reinserted at the first character position of the next line by sensing the
first-word-of-line (A) pulse.
When the ADV LINE key is depressed, PB3 clocks flip-flop A41. 6 reset
during the first F(A) occurring after key depression.
When the cursor appears in
the CE register, the output of NAND-gate A31. 8 goes low to erase the cursor.
The circuit then idles until A enables AND-gate A27.
6.
This pulse is essentially
in coincidence with the last character of retrace, therefore, one character time
later it appears in the CE register attached to the first character of the line.
At the same time the cursor is inserted into the output display logic, the
function-complete flip-flop is re set to develop a Function Complete pulse during
3(CTS+I).
This pulse resets the advance-line function by jamming A41.
6
and
A41. 9 low.
When the NEW LINE key is depressed, the advance-line function is per-
formed because of a line feed code detection in the CE register.
This decoded
output enters through A53.
6
and A53.
8
to jam A41.
6
high and thereby initiate
the function.
The conditions stated in b, c, and d cause an advance-line
.
function when a CR pulse enters through A53. 8 to jam A46.
6
high.
When the
step-right flip-flop is set, and the cursor and A appear
in
coincidence, NAND-gate
A45.8 is enabled to jam A41. 6 high.
This circuit is responsible for automatically
stepping the cursor to a new line each time the cursor is advanced to the last
displayable character of a line.
4-23.3.5 Cursor Reset Function
The cursor reset cursor control function moves the cursor from wherever
it appears on the CRT screen to the frame reset (first character, first line)
position.
In memory, this amounts to placing a low at the input to the CE
register during every CTS except F(A).
This, in turn, assures that wherever the
cursor appears in memory it will be erased.
When the CRT scan is at the
frame reset position, F(A) is gated through to enter the cursor at that position
(see figure 4-43) ..
The cursor reset function is accomplished each time one of the following
occurs:
a.
The operator depresses the CURSR RESET key
b.
A form-feed (FF) control ,ode is received from the CPU without
being preceded by an ESC code
4-114
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