Fluke 9000A-8080 Instruction Manual page 48

8080
5-14
5. Check the output operation of 1/0 port A (contained in U2) as
follows:
a. Perform a write operation to the port A direction register to set all
lines of I/
0
port A (PAO-PA 7) as outputs. The write address is 1081;
write data is FF.
b. Perform a write operation to the port A data register to set all bits
high. The write address is 1080; write data is FF.
c. Check the port A lines (PAO-PA 7) with the probe or scope for all
logic high levels.
d. Repeat step b with 00 as the write data.
e. Repeat step c, checking for all logic low levels.
6.
Check the input operation of I/ 0 port A (contained in U2) as follows:
a. Perform a write operation to the port A direction register to set all
lines of 1/0 port A (PAO-PA7) as inputs. The write address is 1081;
write data is 00.
b. Perform a read operation at the port A data register, address 1080,
while sequentially applying the probe (with high pulses selected) to
each of the port A input pins (pins 8-15 of U2) and observing the
troubleshooter display. The troubleshooter should indicate each high
input of port A.
7. Check the output operation of port B (PBO-PB70) by repeating step 5
and using address 1083 for the port B direction register, and address 1082
for the port B data register.
8. Check the input operation of port B, line PB7 (MAINTST AT) by
repeating step 6. Use address 1083 for the port B direction register and
write data 00 to set line PB7 as an input. Perform the looping read at
address 1082 and apply +5 volts to U2, pin 16.
9. Check operation of the interval timer (contained in U2) by
performing a write operation at address 109C; write data= OF. Verify
that the IRQ output of U2 goes low in response to the write operation.
10. Check for the occurence of the UUT ON signal (produced by the
timing circuits as a result of the low IRQ signal) at the PCB-to-PCB
connector.