Individual Function Flip-Flops; Input And Output Display Logic; Insert And 12-Count Register; 88-Count Register - Raytheon DIDS-400 Series Technical Manual

DIDS-402-2AM13
Individual function flip-flops
Sample sh-:obe flip-flops
Function complete flip-flops
Input and output display logic
Insert and 12-count register
8S-count register
In any cursor control operation, data circulating in the refresh-memory
loop is unaltered by the initiation of the operation. The cursor, which is a
moveable bit circulating in the refresh-memory loop, is always attached to one
character of the message. The purpose of the various cursor control operations
is to locate and move this cursor from one character position to another. This
repositioning may appear on the CRT screen as a cursor movement to one of the
following positions:
Cursor stepped left or right one character position
Cursor stepped up or down to an adjacent line
Cursor advanced to the first character position of the next line
Cursor moved to the frame reset position
Contrary to cursor control operations, the various editing operations are
designed to alter in some manner the data circulating in the refl'esh-mern.ory
loop. This alteration can appear on the CRT screen as one of the following:
Character insert
Line insert
Character delete
Line delete
Line erase
Message erase
As shown in figure 4-17, the editing and cursor control logic can gain access
to refresh-memory data both before and after it enters the delay line or character-
entry register. Since the character-entry register is series connected in the
refre sh-memory loop, one of the 1040 character s circulating in the loop will
always be present in the register. For any of the edit or cursor control operations
to be initiated, the character in the register or the character preparing to enter
the register must have the cursor bit attached to it. In previous explanations
it
was established that only one of the characters in memory has the cursor bit
4-39