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14. Serial Communication and Programmable Communication Interface - An Introduction To Microprocessor 8085

πŸ“– From An Introduction To Microprocessor 8085 β€’ 174 questions available

Practice MCQs for 14. Serial Communication and Programmable Communication Interface. Test your knowledge with carefully crafted questions across easy, medium, and hard difficulty levels.

πŸ”„ Last updated: 2026-07-30

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Easy Questions
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Medium Questions
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πŸ“ Sample Questions

Q1. What is the maximum number of bytes that a single DMA transfer can move without CPU intervention?

πŸ”Ή A. 8192 bytes
πŸ”Ή B. 16384 bytes
πŸ”Ή C. 32768 bytes
πŸ”Ή D. 4096 bytes

πŸ’‘ Difficulty: easy | βœ… Correct: B

Q2. How does the HRQ (HOLD Request) signal interact with the HLDA (HOLD Acknowledge) line during a DMA cycle?

πŸ”Ή A. HRQ is asserted by the CPU and HLDA is ignored
πŸ”Ή B. HRQ is generated by the DMA controller and HLDA is asserted by the CPU to pause it
πŸ”Ή C. HRQ is generated by the DMA controller and HLDA is asserted by the CPU to grant bus control
πŸ”Ή D. HRQ and HLDA are unrelated signals

πŸ’‘ Difficulty: medium | βœ… Correct: C

Q3. Why does the Mode Set Register need to be programmed before starting a DMA transfer on a channel?

πŸ”Ή A. It sets the CPU clock speed
πŸ”Ή B. It defines transfer type, address increment, and auto‑initialization
πŸ”Ή C. It controls the power supply to the DMA controller
πŸ”Ή D. It selects which IRQ line to use

πŸ’‘ Difficulty: hard | βœ… Correct: B

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