Figure 3-12.The 48-label readout word.
X/Y COORDINATE WORD. The X/Y
coordinate word format is shown in figure 3-10. It
is used to define a point on the CRT X/Y grid.
This point may be one of the following: the center
point of a symbol or circle, the starting point of a
line, or the amount of offset in the display. In
addition, the word provides symbol modifier
(size/upper bar position) and blink (2Hz) commands.
DC/DU WORD. The DC/DU word is shown in
u s e d w i t h l i n e s a n d
circles/ellipses. When used with lines it defines the
length and direction of the line. When used with
circles/ellipses it defines the major and minor axis
48 LABEL READOUT WORD. The 48 label
readout word is shown in figure 3-12 and is used to
illuminate the computer controlled action entry panel
(CCAEP) 48 label readouts. It defines the switch
row and column, and the lamp number. It may also
be used to energize or reenergize the PPI buzzer.
Output messages to the display consoles are
composed of one or more of the computer words we
have already discussed. Each message is designed
to define a particular display function. Figure 3-13
lists the display message types and indicates the
in order, that compose the
NORMAL MESSAGE. This message
generated by the computer to locate and describe a
particular track symbol and velocity leader to all the
The X/Y coordinate word provides the
information to position the symbol on the CRT.
The V/C word provides the velocity, category,
identity, and engagement status of the symbol, As
the message is not addressed to any particular
console, the console category selection switching is
used to control the symbol display.
ADDRESSED NORMAL MESSAGE. This
message is the same as a normal message except
that it is preceded by an address word to address the
message to a particular console.
ALPHANUMERIC, HOOK, BALLTAB,
H I S T O R Y D O T ,
A N D P O I N T E R
MESSAGES. These addressed messages consist of
an address word and an X/Y coordinate word. They
are designed to display the particular alphanumeric,
or indicated symbol on the
addressed console only.
LINES MESSAGE. This message is designed
to draw a line on the PPI display. The message
consists of a DC/DU coordinate word to define the
slope and length of the line, an X/Y coordinate word
to specify the starting point, and a V/C word to
identify the type of line.
ADDRESSED LINES MESSAGE. This
message (not shown) is the same as the lines
message except that it is preceded by an address
word to address the message to a particular console.