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📝 Interfacing of 8251A in 8085A Microprocessor

📖 From An Introduction To Microprocessor 8085 • 14. Serial Communication and Programmable Communication Interface • 10 questions available

Practice MCQs for Interfacing of 8251A in 8085A Microprocessor. Test your knowledge with carefully crafted questions across easy, medium, and hard difficulty levels.

🔄 Last updated: 2026-07-30

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Easy Questions
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Medium Questions
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Hard Questions

📝 Sample Questions

Q1. How many bits of the terminal count register are used to store the number of bytes to be transferred?

🔹 A. 16-bit
🔹 B. 8-bit
🔹 C. 14-bit
🔹 D. 12-bit

💡 Difficulty: easy | ✅ Correct: C

Q2. How does the Address Enable (AEN) pin affect the operation of the 8257 DMA controller?

🔹 A. AEN disables the address bus so the DMA cannot access memory.
🔹 B. AEN enables the CPU to supply addresses while DMA is idle.
🔹 C. AEN allows the DMA controller to place addresses on the bus during a transfer.
🔹 D. AEN forces the DMA controller to use fixed addresses only.

💡 Difficulty: medium | ✅ Correct: C

Q3. A designer connects two peripherals to channels 0 and 1 of the 8257. Channel 0 must transfer 12 K bytes and channel 1 must transfer 4 K bytes simultaneously. Which MODE register setting ensures both channels operate in cascade mode without bus contention?

🔹 A. Set both channels to single‑transfer mode (00) and enable auto‑initialize.
🔹 B. Configure channel 0 as block‑transfer (01) and channel 1 as demand‑transfer (10).
🔹 C. Program both channels for cascade mode (11) and enable address increment.
🔹 D. Use demand‑transfer for channel 0 and block‑transfer for channel 1.

💡 Difficulty: hard | ✅ Correct: A

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🔗 Related Topics

📝 Serial Data Communication IC 8251 in 8085A Microprocessor📝 Modem IC 8251 in 8085A Microprocessor📝 Serial Communication Standard IC 8251 in 8085A Microprocessor📝 Asynchronous Software Approach IC 8251 in 8085A Microprocessor📝 Programmable Communication Interface IC 8251 in 8085A Microprocessor
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