🏠 Home > An Introduction To Microprocessor 8085 > 14. Serial Communication and Programmable Communication Interface > Modem Control in 8085A Microprocessor
← Back to 14. Serial Communication and Programmable Communication Interface

📝 Modem Control in 8085A Microprocessor

📖 From An Introduction To Microprocessor 8085 • 14. Serial Communication and Programmable Communication Interface • 8 questions available

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

🔄 Last updated: 2026-07-30

2
Easy Questions
4
Medium Questions
2
Hard Questions

📝 Sample Questions

Q1. What is the maximum number of bytes that a single DMA transfer can handle using the 8257 controller?

🔹 A. 16384 bytes
🔹 B. 32768 bytes
🔹 C. 8192 bytes
🔹 D. 4096 bytes

💡 Difficulty: easy | ✅ Correct: A

Q2. A system must move 20 KB of data from memory to a peripheral using the 8257. Can a single DMA transfer satisfy this requirement?

🔹 A. Yes, because 20 KB < 16 KB
🔹 B. No, because it exceeds the 16 KB limit
🔹 C. Yes, using two consecutive DMA cycles
🔹 D. No, DMA cannot transfer more than 8 KB

💡 Difficulty: medium | ✅ Correct: B

Q3. How does the HRQ (HOLD Request) line interact with the CPU during a DMA transfer?

🔹 A. HRQ forces the CPU to stop; HLDA signals that the bus is released
🔹 B. HRQ is ignored by the CPU and has no effect
🔹 C. HRQ directly moves data without CPU involvement
🔹 D. HRQ toggles the RESET line to restart the system

💡 Difficulty: hard | ✅ Correct: A

⬆️ View all questions in the quiz below

🔗 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
🚀 Start Quiz 📝 Practice Mode