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📝 INTEL Programmable Keyboard/Display Interface 8279

📖 From An Introduction To Microprocessor 8085 • 10. Programmable Keyboard and Display Interface: 8279 • 8 questions available

Practice MCQs for INTEL Programmable Keyboard/Display Interface 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 system needs to generate a periodic interrupt using counter 0. Which pin should be connected to the interrupt line?

🔹 A. OUT0 (Pin 10)

🔹 B. GATE0 (Pin 11)

🔹 C. CLK0 (not listed)

🔹 D. CS (Pin 21)

💡 Difficulty: easy | ✅ Correct: A

Q2. To write a mode word that configures counter 1 for square‑wave operation, which combination of control signals must be active? Use 0 for low and 1 for high.

🔹 A. CS=0, RD=1, WR=0, A1=1, A0=1

🔹 B. CS=0, RD=0, WR=0, A1=1, A0=0

🔹 C. CS=0, RD=1, WR=1, A1=0, A0=1

🔹 D. CS=1, RD=1, WR=0, A1=1, A0=1

💡 Difficulty: medium | ✅ Correct: A

Q3. If GATE2 is mistakenly wired to the same line as OUT1, what functional problem is most likely to occur?

🔹 A. Counter 2 will never start because its gate is tied to an output

🔹 B. Counter 1 cannot be gated, disabling its operation

🔹 C. Both counters will be gated simultaneously, causing unintended synchronization

🔹 D. The device will enter a disabled 3‑state condition

💡 Difficulty: hard | ✅ Correct: C

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🔗 Related Topics

📝 Block Diagram of 8279 📝 Functional Description of 8279 📝 Key Board San of 8279 📝 Scanned Keyboard of 8279 📝 Two key Lockout of 8279

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