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|  MIL-N-85005A(AS)
3.5.7.4.4
Input/Output - As a minimum the NC shall contain 8
input data channels, 8 output data channels, 32 input discretes, and 32 output
discretes. The NC shall have the expansion capability of 16 output channels,
16 input channels, 64 input discretes and 64 output discretes. All input
lines will be 2 wire differential line receivers (Fairchild A9615 or
equivalent) terminated with 130 ohms dc. All output lines will be 2
wire differential line drivers (Fairchild A9614 or equivalent). In
addition to the differential input discretes there shall be three high-
level, single-ended logic level discretes.
3.5.7.4.4.1
Data Channels - All data channels shall transfer 16 bit
binary words serially, least significant bit first, at a rate of 1.0 MHz. The
I/O clock shall supply all serial data transfer rates. For data output
from the NC, the data line shall be stable for 250 nanoseconds after the
trailing edge of the clock pulse.
3.5.7.4.4.2
Differential Discretes - Discretes shall be differential
signals in accordance with Figure 18. Input discretes are sensed as steady
logic "1" or "0" on any of 32 lines. Output discretes shall be of two
types:
(1) Set discrete line to logic "1" or logic "O".
(2) Supply 250 nanosecond logic "1" pulse.
3.5.7.4.4.2.1 Interrupts - The NC shall accept a minimum of eight levels
of interrupts - designated level 1 through level 8. Interrupt priority
shall be from level 1 through level 8 in decreasing priority - where priority
of an interrupt level identifies which interrupt will be serviced first when
more than one interrupting event occurs concurrently.
Clock - The NC shall have a 16 MHz clock whose accuracy
3.5.7.4.4.3
shall be greater than 50 parts per million.
3.5.7.4.4.4
DMA Channel - The NC shall provide a 16-bit parallel
one half duplex, differential DMA channel which shall be capable of 8-bit
data byte addressing. The channel operates autonomously on a "cycle stealing"
basis. The maximum data rate is 570,000 16-bit words per second.
Built-In Test - BIT features shall be incorporated
3.5.7.4.4.5
into the NC to provide GO/NO-GO indications of the NC readiness automatically
on the NC.
3.5.7.4.4.6
Software Diagnostic Capability - The NC shall be logically
and electrically designed to facilitate the isolation of a malfunctioning
of three or less modules through diagnostic programming.
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