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Description of Multipurpose Display Logic Operation |
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|  MIL-D-81347C(AS)
analog modes described in 3.5.3.4.1.4.3.1. 7(2) and 3.5.3.4.1.4.3.1. 7(9). If an EOD command is
received in the cycle immediately after the alarm occurs, operation at a 20 Hz rate continues: if no
EOD occurs during either the first or second cycle, then the MPD Logic will generate its own reset
upon receipt of the second 40 Hz Sync pulse.
(9) Control Field Code 11 - The Set Position Word Command
Field 11 shall cause the Logic Unit to select and display the Raw Radar Video information from the
AN/APS-80 ( ). The X and Y coordinates presented in the Set Position word having a Control Field of
11 shall cause the X and Y Deflection circuits to center the radar presentation on the specified X and Y
coordinates. This radar presentation can be either a PPI or "A" scan presentation, depending on the
function selected.
(10) Control Field Codes 12 and 13 - The Set Position Words with
Control Field Codes 12 and 13 shall select either the 40 Hz or 57.1 Hz frame sync signals for synchroni-
zation among the MPD, central computer, and display associated analog devices. A Set Position word
containing a Control Field Code 12 shall be transmitted to the MPD Logic each time there is a change in
display presentation from LLLTV to a display format other than LLLTV. Upon receipt of this code
the MPD Logic shall transmit a logical "0" on the LLLTV Active line to the MTL to select the 40 Hz
Frame Sync signal. A Set Position Word containing a Control Field Code 13 shall be transmitted to
the MPD Logic each time there is a change in display presentation to LLLTV from a display format other
than LLLTV. Upon receipt of this code the MPD Logic shall transmit a logical "1" on the LLLTV
Active line to the MTL to select the 57.1 Hz Frame Sync signal.
Diagnostic - The 16-bit diagnostic instruction word shall initiate
3.5.3.4.1.4.3.1.8
diagnostic operation in the MPD Logic.
3.5.3.4.1.4.3.2
Input Computer Signals - Input signals to the computer shall be in
the form of 30-bit parallel words plus control lines. These data lines shall provide diagnostic informa-
tion to the computer.
Description of Multipurpose Display Logic Operation - The
3.5.3.4.1.5
sequence and timing of each of the operations performed by the MPD Logic are outlined in the following
paragraphs.
Load Data - In the On-Line Mode of operation, data is trans-
3.5.3.4.1.5.1
ferred from the computer to the MPD Logic on a Request - Acknowledge basis as described in
Appendix I. Upon sensing the presence of an Output Acknowledge signal, the Logic clears its input
register and loads the new 30-bit computer word. If the Inhibit bit is marked, the data is discarded
and a new word is requested except in the case of the Typewriter mode. If the Inhibit bit is not
marked, the Logic will operate on the word in accordance with the coding as explained below. In the
various test modes of operation, data is loaded from the internal test pattern generator in a manner
analogous to computer data.
Plot Character - The MPD Logic decodes this command, stores
3.5.3.4.1.5.2
and sends the position information to the MPD, sends the character selection information to the MPD
and waits 16 microseconds for deflection settling. Then the Logic sends a 24 microsecond Character
Unblank signal to the MPD. At the end of this period, another request for information from the Com-
puter is generated. Positioning information is stored separately from the input register because in
some other modes, it must be remembered between operations. Figure 103 illustrates timing con-
straints for the Plot Mode.
3.5.3.4.1.5.3
Set Position - The Logic interprets this command, stores the
position information and sends it to the display, and further interprets the Control Field Code to de-
termine the subsequent operation. Some operations, such as Analog Channels 1, 2, 3, or 4 in the case
of a Raw Radar Video presentation, or End of Data, require no additional information from the com-
puter. For analog presentations, the Logic, upon receipt of the Set Position word, transmits the
proper analog deflection enable signal, spot focus signal, and position and character (code 00) bits to
the MPD. Sixteen microseconds later, the proper video enable signal is transmitted to the M PD. For
an end of data, the Logic inhibits the generation of the Output Data Request until the 40 Hz Sync signal.
171
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