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In the I/O mode, the 8255 ports work as

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Answer & Explanation

Correct AnswerC. Programmable I/O ports

Quick Explanation

In I/O mode, the 8255 Programmable Peripheral Interface configures Ports A, B and C as programmable input/output ports according to the control word and selected Mode 0, 1 or 2 behavior.

Formula / Key Relation

8255 I/O modes:

Mode 0: simple I/O

Mode 1: strobed I/O

Mode 2: bidirectional bus (Port A)

Detailed Explanation

Concept & Reasoning

The 8255 has two broad control formats: I/O mode and BSR (Bit Set/Reset) mode. In I/O mode, port directions and handshake capabilities are programmed. Port C bits may also carry handshake/status signals in strobed modes.

How to Solve It in the Exam

8255 name itself: Programmable Peripheral Interface.

Important Exam Point

Do not confuse I/O mode with BSR mode for individual Port C bits.

Related Revision Path

This question sits in the revision path Microprocessors and Interfacing → 8255 PPI → Operating Modes .

Programmable I/O Ports explanatory diagram

Quick Trick

8255 name itself: Programmable Peripheral Interface.

Common Mistake

Calling the ports 'only output' despite programmable direction.

Exam Tip

Do not confuse I/O mode with BSR mode for individual Port C bits.

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Exam Path

Knowledge Path

Study concept · Programmable I/O Ports →Practice concept Practice topic

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