signals drive a functional-OR gate consisting of U13D, U13E, and U15A.
These functional-OR components respond to CS7 and the IN strobe by
producing a low clock pulse at U9C (pin 8). This clock strobe is ap-
plied to AND gate U5D (pin 13) via U9C (enabled by the low output of
reset latch 14A) and U9B (enabled by the low output of inhibited EXT
click gate U9A). Gate U5D, enabled by the absence of an EXT LOAD
pulse, transfers the microprocessor clock to register U6. U6 responds
by shifting one bit out (pin 6) and onto input port. 7 (IB70). The
microprocessor receives this bit from the I/O bus ( I/O0 line) and
loads it into the appropriate memory data file during a subsequent
A total of 64 microprocessor clocks are provided to serially trans-
fer the contents of register U6 into the designated storage location
of the memory data file. The microprocessor then generates an output
port 6 code, producing a CS6 strobe which sets computer data input
latch U14A. Set, latch U14A configures the interface logic circuits
of CCA A5 for the next 64-hit receiver command update word from the
n. Miscellaneous Port Selection and Decoding. Output interface
CCA A5 performs some receiver control -port decoding functions in ad-
dition to providing external interface (see figures 5-14 and FO-13).
These functions include:
(1) Write strobe 9, CCA A5 combines an OUT strobe with active
CS9 decoder output to produce WR9 (write strobe 9). This positive
true strobe enables I/O bus data to select a front panel frequency
display digit as shown in figure 5-14.
(2) Frequency display values. The numeric value of the digit
selected in paragraph (1) above is determined by the output port 2
drive (OB20 thru OB23) to buffers U29C thru U29F, U30A thru U30C, U21C
thru U21F, and U22A thru U22D. (Output port 2 (OB20 thru 0B23 ) data
have been latched onto those lines from respective I/0 buss I/O 0 thru
I/O 3 lines during a previous instruction cycle.) The resulting
bed-coded ABCD output lines drive the selected front panel frequency
display digit to provide the numeric value shown in table 5-8.
(3) Decimal point placement. Output port 5 provides the decimal
point placement data defined in table 5-2. The microprocessor writes
these data onto the OB50 thru OB53 lines. Buffers U21C thru U21F and
U22A thru U22D invert the l-of-4 coded output port 5 data to provide
DSO thru DS3 decimal point drive to the front panel TUNING FREQUENCY
(MHZ) display. This drive positions the decimal point according to
the code which is defined in the output port 5 column of table 5-2.
o. Miscellaneous Control and Receiver Control Clocks. Control
CCA A7 provides receiver control clock, control of panel and keyboard
lamp intensity, microprocessor power-on reset, intercom audit) output
level control, and control decoding (see figure FO-14).
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