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📝 Status Register(IN Operation) of 8279

📖 From An Introduction To Microprocessor 8085 • 10. Programmable Keyboard and Display Interface: 8279 • 11 questions available

Practice MCQs for Status Register(IN Operation) of 8279. 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. A microcontroller must read the current count from counter 0 of an 8253 timer. Which combination of control signals should be asserted?

🔹 A. CS=0, RD=1, WR=0, A1=0, A0=0 (Load counter 0)

🔹 B. CS=0, RD=0, WR=1, A1=0, A0=0 (Read counter 0)

🔹 C. CS=0, RD=0, WR=1, A1=0, A0=1 (Read counter 1)

🔹 D. CS=0, RD=1, WR=0, A1=1, A0=0 (Load counter 2)

💡 Difficulty: easy | ✅ Correct: B

Q2. To generate a 1 ms periodic interrupt using counter 2, which pin must be connected to the interrupt line and what control signals are required to load the counter with the appropriate divisor?

🔹 A. Connect OUT 2; assert CS low, WR low, RD high, A1=1, A0=0

🔹 B. Connect GATE 2; assert CS low, WR low, RD high, A1=1, A0=0

🔹 C. Connect CLK 2; assert CS low, WR low, RD high, A1=1, A0=0

🔹 D. Connect OUT 2; assert CS low, RD low, WR high, A1=1, A0=0

💡 Difficulty: medium | ✅ Correct: D

Q3. A designer mistakenly ties pin 21 (CS) to VCC instead of pulling it low when accessing counter 0. What is the most likely result?

🔹 A. The 8253 will be permanently disabled, ignoring all commands

🔹 B. Counter 0 will always read as zero

🔹 C. The mode‑word register will be overwritten with garbage data

🔹 D. No effect; the device will operate normally

💡 Difficulty: hard | ✅ Correct: A

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🔗 Related Topics

📝 INTEL Programmable Keyboard/Display Interface 8279 📝 Block Diagram of 8279 📝 Functional Description of 8279 📝 Key Board San of 8279 📝 Scanned Keyboard of 8279

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