Engineering Questions with Answers - Multiple Choice Questions

MCQs on PIO 8255 (Programmable Input – Output Port)

1 - Question

Programmable peripheral input-output port is another name for
a) serial input-output port
b) parallel input-output port
c) serial input port
d) parallel output port

View Answer

Answer: b
Explanation: The parallel input-output port chip 8255 is also known as programmable peripheral input-output port.




2 - Question

Port C of 8255 can function independently as
a) input port
b) output port
c) either input or output ports
d) both input and output ports

View Answer

Answer: c
Explanation: Port C can function independently either as input or as output ports.




3 - Question

All the functions of the ports of 8255 are achieved by programming the bits of an internal register called
a) data bus control
b) read logic control
c) control word register
d) none of the mentioned

View Answer

Answer: c
Explanation: By programming the bits of control word register, the operations of the ports are specified.




4 - Question

The data bus buffer is controlled by
a) control word register
b) read/write control logic
c) data bus
d) none of the mentioned

View Answer

Answer: b
Explanation: The data bus buffer is controlled by read/write control logic.




5 - Question

The input provided by the microprocessor to the read/write control logic is
a) RESET
b) A1
c) WR(ACTIVE LOW)
d) All of the mentioned

View Answer

Answer: d
Explanation: RD(ACTIVE LOW), WR(ACTIVE LOW), A1, A0, RESET are the inputs provided by the microprocessor to the read/write control logic of 8255.




6 - Question

The device that receives or transmits data upon the execution of input or output instructions by the microprocessor is
a) control word register
b) read/write control logic
c) 3-state bidirectional buffer
d) none of the mentioned

View Answer

Answer: c
Explanation: 3-state bidirectional buffer is used to receives or transmits data upon the execution of input or output instructions by the microprocessor.




7 - Question

The port that is used for the generation of handshake lines in mode 1 or mode 2 is
a) port A
b) port B
c) port C Lower
d) port C Upper

View Answer

Answer: d
Explanation: Port C upper is used for the generation of handshake lines in mode 1 or mode 2.




8 - Question

If A1=0, A0=1 then the input read cycle is performed from
a) port A to data bus
b) port B to data bus
c) port C to data bus
d) CWR to data bus

View Answer

Answer: b
Explanation: If A1=0, A0=1 then the input read cycle is performed from port B to data bus.




9 - Question

The function, ‘data bus tristated’ is performed when
a) CS(active low) = 1
b) CS(active low) = 0
c) CS(active low) = 0, RD(active low) = 1, WR(active low) = 1
d) CS(active low) = 1 OR CS(active low) = 0, RD(active low) = 1, WR(active low) = 1

View Answer

Answer: d
Explanation: The data bus is tristated when chip select pin=1 or chip select pin=0 and read and write signals are high i.e 1.




10 - Question

The pin that clears the control word register of 8255 when enabled is
a) CLEAR
b) SET
c) RESET
d) CLK

View Answer

Answer: c
Explanation: If reset pin is enabled then the control word register is cleared.

Get weekly updates about new MCQs and other posts by joining 18000+ community of active learners