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📝 DMA Interfacing Circuit of 8257

📖 From An Introduction To Microprocessor 8085 • 12. Direct Memory Access Controller: 8257 • 21 questions available

Practice MCQs for DMA Interfacing Circuit of 8257. Test your knowledge with carefully crafted questions across easy, medium, and hard difficulty levels.

🔄 Last updated: 2026-07-30

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Q1. What is the name of the programmable DMA controller used with the 8085 microprocessor?

🔹 A. 8255

🔹 B. 8257

🔹 C. 8253

🔹 D. 8259

💡 Difficulty: easy | ✅ Correct: B

Q2. A system uses an 8257 DMA controller to transfer a block of 1024 bytes from memory address \\(0x2000\\) to an I/O device. Which register pair must be programmed with the starting address?

🔹 A. Page register

🔹 B. Address register

🔹 C. Count register

🔹 D. Mode register

💡 Difficulty: medium | ✅ Correct: B

Q3. In a system with 8085 CPU, the 8257 DMA controller, and two peripherals, a bug causes the CPU to hang after a DMA transfer. Investigation shows that the HLDA line is never released. Which of the following is the most probable cause?

🔹 A. The CPU did not receive the HOLD signal

🔹 B. The DMA controller failed to assert the Acknowledge

🔹 C. The CPU's HOLD line is held low due to faulty wiring

🔹 D. The peripheral did not de‑assert its DRQ

💡 Difficulty: hard | ✅ Correct: C

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🔗 Related Topics

📝 Block Diagram of 8257 📝 DMA Channels of 8257 📝 Data Bus Buffer of 8257 📝 Read/ Write Logic of 8257 📝 Control Logic of 8257

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