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📝 Display Interface of 8279

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

Practice MCQs for Display Interface 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. To read the count from counter 2, which set of control signal levels must be asserted?

🔹 A. CS low, RD low, WR high, A1 high, A0 low

🔹 B. CS low, RD high, WR low, A1 low, A0 low

🔹 C. CS high, RD low, WR low, A1 high, A0 high

🔹 D. CS low, RD low, WR low, A1 low, A0 high

💡 Difficulty: easy | ✅ Correct: A

Q2. A designer connects pins 13‑15 of the 8253 to a peripheral that needs a clock pulse every 10 µs. Which pin provides the clock input for counter 1, and what must be the state of the GATE 1 pin for the counter to count continuously?

🔹 A. Pin 13, GATE 1 low

🔹 B. Pin 15, GATE 1 high

🔹 C. Pin 14, GATE 1 low

🔹 D. Pin 15, GATE 1 low

💡 Difficulty: medium | ✅ Correct: B

Q3. In a system, the CS pin is inadvertently left floating (neither driven low nor high). Explain the likely effect on all read/write operations and suggest a hardware fix.

🔹 A. Device will always be enabled, causing bus contention

🔹 B. Device will never respond, leading to no operation

🔹 C. Device may randomly enable, causing intermittent failures

🔹 D. Device will ignore address lines but still respond to data

💡 Difficulty: hard | ✅ Correct: C

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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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