← Back to 14. Serial Communication and Programmable Communication Interface

📝 Serial Communication Standard IC 8251 in 8085A Microprocessor

📖 From An Introduction To Microprocessor 8085 • 14. Serial Communication and Programmable Communication Interface • 25 questions available

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

🔄 Last updated: 2026-07-30

Easy Questions

Medium Questions

Hard Questions

📝 Sample Questions

Q1. How many bytes can be transferred in a single DMA operation using the 8257's terminal count register?

🔹 A. 8 KB

🔹 B. 12 KB

🔹 C. 16 KB

🔹 D. 32 KB

💡 Difficulty: easy | ✅ Correct: C

Q2. In what way does the DMA controller's internal Data Bus Buffer improve data transfer efficiency?

🔹 A. It stores data temporarily to avoid bus contention

🔹 B. It converts parallel data to serial form

🔹 C. It provides error correction for transmitted bytes

🔹 D. It doubles the data width for faster transfers

💡 Difficulty: medium | ✅ Correct: D

Q3. Analyze why the 8257 provides four separate channels but only three DRQ inputs (DRQ0‑DRQ3) are listed; how does the controller handle the missing channel?

🔹 A. Channel 3 shares DRQ3 with channel 4 through internal multiplexing

🔹 B. Channel 4 is a software‑only channel without a physical DRQ line

🔹 C. Channel 0 uses two DRQ pins to emulate four channels

🔹 D. All four channels use the same DRQ line with time‑division arbitration

💡 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 📝 Asynchronous Software Approach IC 8251 in 8085A Microprocessor 📝 Programmable Communication Interface IC 8251 in 8085A Microprocessor 📝 Block Diagram of 8251A in 8085A Microprocessor

🚀 Start Quiz 📝 Practice Mode