8051 I/O MCQs

Practice 8051 I/O MCQs with four options, answers and explanations for focused Electronics & Telecommunication Engineering revision.

Question 1

Microprocessors & Microcontrollers8051 I/O

How many parallel I/O ports are provided by the classic 8051?

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Correct Answer: C. 4

Explanation: The classic 8051 provides four 8-bit ports: P0, P1, P2 and P3.

Reference: Standard microprocessors and microcontrollers: 8051 i/o

Question 2

Microprocessors & Microcontrollers8051 I/O

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Correct Answer: D. 32

Explanation: Four ports × 8 bits per port = 32 I/O lines.

Reference: Standard microprocessors and microcontrollers: 8051 i/o

Question 3

Microprocessors & Microcontrollers8051 I/O

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Correct Answer: A. Port 0

Explanation: Classic 8051 Port 0 uses open-drain outputs and needs external pull-ups for general-purpose I/O operation.

Reference: Standard microprocessors and microcontrollers: 8051 i/o