Microprocessors Questions and Answers – PIO 8255 (Programmable Input – Output Port)

This set of Microprocessor Multiple Choice Questions & Answers (MCQs) focuses on “PIO 8255 (Programmable Input – Output Port)”.

1. 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
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2. 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
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3. 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
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4. The data bus buffer is controlled by
a) control word register
b) read/write control logic
c) data bus
d) none of the mentioned
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5. 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
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6. 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
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7. 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
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8. 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
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9. 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
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10. The pin that clears the control word register of 8255 when enabled is
a) CLEAR
b) SET
c) RESET
d) CLK
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