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|  MIL-D-81347C(AS)
(11) The peripheral equipment drops the data at its convenience.
The DIM shall not transmit any further data from this peripheral equipment to the computer until the
.
equipment drops and then sets its Enter line indicating new data.
3.5.1.4.1.3.2
Timing, Priority and Initialization
(1) Since the peripheral equipments, which communicate with
the computer via the DIM, operate independently of each other, a number of equipments may raise
their Enter lines (indicating data is ready for transmission to the computer) simultaneously. The DIM
shall sequentially scan the Enter lines from the peripheral equipments, stopping and entering the data
from the first peripheral equipment with its Enter line set. The trailing edge of the Input Acknowledge
shall start the DIM scanning again: the scan shall commence at the Enter line of the next peripheral
equipment in the normal scan sequence. The order in which the DIM scans the peripheral equipments
is designated by the channel numbers assigned to the equipments. There shall be no priority in the
DIM, except for channel 11; if a number of peripheral equipments simultaneously set their Enter lines,
the peripheral equipment serviced first by the DIM shall depend on the position of the scanner; e.g. , if
peripheral equipments 1, 2, and 8 simultaneously set their Enter lines and the scanner normally scans
sequentially from channel O through 15 and the scanner is at channel 6, the data from channel 8 shall
be entered first and then channels 1 and 2 shall be serviced in that order before 8 can be serviced
again. Upon receipt of a channel 11 Enter, the DIM shall complete the transmission of any channel
being processed and then transmit channel 11 data.
(2) The time required for the DIM to scan all the Enter lines
from the 16 peripheral equipments, when none of the Enter lines is set, shall not exceed 64 micro-
seconds,
(3) The time between the detection of an active Enter line by the
scanner and the raising of the Input Data Request line to the computer shall not exceed six micro-
seconds,
(4) The DIM shall be self-initializing; i.e. , when power is
applied to the DIM, no spurious data shall be transmitted to the computer and the DIM shall be ready
for normal operation.
3.5. 1.4.1.4
Test Loops
3.5. 1.4.1.4.1
In-Flight Performance Monitoring Channels - Two of the channels
of the DIM shall be designated as test channels. The setting of the Enter and Data lines for these
channels shall be controlled by the computer program via the DOM. The DIM shall scan the Enter
lines and transmit the data from these channels the same as it would for any other peripheral equip-
ment. This loop operation, computer to DOM to DIM to computer, shall permit the computer program
to monitor automatically the performance of the DOM and DIM. The test loops shall be utilized for in-
flight performance monitoring and diagnostic programs.
Interface Requirements - Refer to Figure 2, the functional flow
3. 5.1.4.1.5
diagram for the DIM.
3. 5.1,4.1.5.1
Format of Input Word to Computer from Digital Input Multi-
plexer - Refer to the format shown in Figure 1.
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