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📝 Scanned Keyboard of 8279

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

Practice MCQs for Scanned Keyboard of 8279. Test your knowledge with carefully crafted questions across easy, medium, and hard difficulty levels.

🔄 Last updated: 2026-07-30

2
Easy Questions
4
Medium Questions
2
Hard Questions

📝 Sample Questions

Q1. A designer connects pin 11 (GATE0) to ground to keep counter 0 disabled. Which pin should be observed to confirm that counter 0 is not counting?

🔹 A. Pin 10 (OUT0)
🔹 B. Pin 12 (GROUND)
🔹 C. Pin 21 (CS)
🔹 D. Pin 22 (RD)

💡 Difficulty: easy | ✅ Correct: A

Q2. To load counter 2 with the value 5000, which control signal levels must be set on CS RD WR A1 and A0?

🔹 A. CS=0 RD=0 WR=0 A1=1 A0=0
🔹 B. CS=0 RD=1 WR=0 A1=1 A0=0
🔹 C. CS=0 RD=1 WR=1 A1=1 A0=0
🔹 D. CS=1 RD=1 WR=0 A1=1 A0=0

💡 Difficulty: medium | ✅ Correct: B

Q3. If both address lines A0 and A1 are high, CS is low, WR is low, and RD is high, what operation does the 8253 perform and which counter is affected?

🔹 A. Load counter 0
🔹 B. Load counter 1
🔹 C. Write Mode Word
🔹 D. Read counter 2

💡 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📝 Two key Lockout of 8279
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