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|  MIL-D-81347C(AS)
Display Instruction Word - Figures 142 through 145 show the
3.5.4.4.3.5.1.1
digital display instruction word formats. In all of these words bit 14 will be a logic 0 indicating a
display instruction word and not a diagnostic instruction word. Bits 26 through 29 in all of the display
words will define the display function. The list of display actions defined by the various function codes
is shown in the following tabulation:
Function Performed
Function Code Bits
Binary
26
28 27
29
octal
No Operation
0
0
00
0
0
.
Set Position - Location Beam
01
1
0
0
0
Print 1 character - No 2nd character
1
02
0
0
0
Print 2 characters and Point
1
1
03
0
0
Print characters - No Point (Type Format)
1
0
04
0
0
Display Vector
1
1
0
05
0
Display Azimuth Vector
1
1
0
06
0
1
Display Circle
1
07
1
0
EOD
0
10
1
0
0
1
Identical to Code 02 but Flashing
12
0
0
1
1
1
Identical to Code 03 but Flashing
13
1
0
Identical to Code 04 but Flashing
14
1
0
0
1
No Operation - Function Code 00- When a word containing this
3.5.4.4.3.5.1.1,1
code is received from the computer, the Auxiliary Display Logic shall inhibit the normal processing of
the word and request a new computer word.
Set Position Word - Function Code 01 - The Set Position word,
3.5.4.4.3.5.1.1.2
Figure 142, will contain the "X and Y components of the positioning data for all vectors, circles, and
characters. The X componet is contained in bits 15 through 22, where bit 22 is the MSB and bit 15
the LSB. The Y component is contained in bits 0 through 7, where bit 7 is the MSB and bit O the LSB.
The eight binary bits of horizontal deflection data and eight binary bits of vertical deflection data shall
be utilized to define a Cartesian coordinate system with the origin at the center of the display. All of
the X and Y coordinate data will be expressed in the one's complement system. The maximum positive
deflection for the 7.6 inch usable diameter of the 9-inch diameter CRT is defined by 177 in the octal
code; the maximum negative deflection is defined as 200 in the octal code (see Figure 140). The use
of the eight binary bit magnitude in conjunction with the 8-inch usable CRT diameter will provide a
plotting position selection capability of approximately 0.0312 inch apart.
Character Word - A character word, Figure 143, will contain
3.5.4.4.3.5.1.1.3
one or two character data codes, C1 and C2, plus the Character Function Code. The Character Func-
tion Code will describe the manner in which this Character Word is to be processed. . Character 2
will be contained in bits 15through 20 with bit 20 as the MSB and bit 15 as the LSB. Character 2 will
be contained in bits O through 5, with bit 5 as the MSB and bit 0 as the LSB.
(1) Function Code (02) - This will be a one character message
pertaining only to special characters. A point shall first be plotted at the X, Y position contained in
the previous positioning word, and one of the special characters shall then be drawn with its center at
this point. The second character will always be blank in this mode of operation. Special characters
will be defined by codes 0.0, 13, 14, 15, 16, 17, 41 and 44.
249
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