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📝 Initialization of 8251A in Asynchronous Mode in 8085A Microprocessor

📖 From An Introduction To Microprocessor 8085 • 14. Serial Communication and Programmable Communication Interface • 21 questions available

Practice MCQs for Initialization of 8251A in Asynchronous Mode 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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📝 Sample Questions

Q1. What number of bits are used in the terminal count register to specify the byte count for a DMA transfer?

🔹 A. 8 bits

🔹 B. 14 bits

🔹 C. 16 bits

🔹 D. 32 bits

💡 Difficulty: easy | ✅ Correct: B

Q2. When configuring the 8251A for 8‑data‑bit, no‑parity, 1‑stop‑bit communication, which combination of control‑word bits is correct?

🔹 A. \(\text{M}=0,\ \text{P}=1,\ \text{S}=1\)

🔹 B. \(\text{M}=1,\ \text{P}=0,\ \text{S}=0\)

🔹 C. \(\text{M}=0,\ \text{P}=0,\ \text{S}=0\)

🔹 D. \(\text{M}=1,\ \text{P}=1,\ \text{S}=0\)

💡 Difficulty: medium | ✅ Correct: C

Q3. Why must the DLAB (Divisor Latch Access Bit) be cleared after setting the baud‑rate divisor for the 8251A?

🔹 A. To enable transmitter interrupts

🔹 B. To allow access to the data register

🔹 C. To prevent accidental modification of the divisor

🔹 D. To switch to synchronous mode

💡 Difficulty: hard | ✅ Correct: C

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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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