NorthStar HORIZON Manual page 77

PA1~LLEL INTERFACE CONFIGURATION HEADER
ThE' parallel interface control functions are determined by the
corlfiguration of the 14-pin Parallel Port DIP header at location
9C The pins of this header have the following assignments:
pirl Description
1 Logic LOW (ground)
2 Output Acknowledge signal from pir 7 of the parallel output
interface connector.
3 Inverted Output Acknowledge signal from pin 7 of the
parallel output interface connector.
4 Available for driving an extra signal onto pIn 8 of the
parallel output interface connector.
S Available for driving an extra signal onto pIn 8 if the
parallel input interface connector.
6 Input Strobe Signal from pIn 6 of the parallel input
interface connector . .
7 Inverted Input Strobe Signal from pIn 6 of the parallel
input interface connector.
8 Logic HIGH.
9
Tied to clock of parallel input interface flag flip-flop.
10 Free.
11 Free.
12 This signal indicates execution by the processor of a data
output instruction to the parallel output port (HIGH while
valid data on bus).
13 Tied to the clock of the parallel output interface flag
f 1
i p- flop.
14 Tied to the output enable control of the parallel output
interface data latch.
PARALLEL OUTPUT EXAMPLE
Different printers have different interfacing requirements. The
following example is for a hypothetical printer. To configure
for output to a parallel printer:
A. Connect pin 1 to pin 14 of the header to permanently enable
the data output latch.
B.
Connect pin 2 to pin 13 to cause a positive-going edge of
the acknowledge signal to set the output flag flip-flop.
(Connect pin 3 to pin 13 if a negative-going edge should set
the flag flip-flop.)
C. Connect pin 4 to pin 12 to signal the printer of each new
data byte to be output.
D. Construct a cable from the IS-pin Parallel Output Connector
to the printer which connects;
7~
North Star HORIZON Computer