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📝 Programming of 8279

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

Practice MCQs for Programming 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 generate a periodic interrupt using counter 0 of the 8253. Which pin provides the output signal that can be connected to the interrupt line?

🔹 A. OUT 0 (pin 10)

🔹 B. GATE 0 (pin 11)

🔹 C. CLK 0 (pin 9)

🔹 D. CS (pin 21)

💡 Difficulty: easy | ✅ Correct: A

Q2. To load a new count value into counter 2 while the system is operating, which combination of control signals must be asserted according to the 8253 control‑signal table?

🔹 A. CS=0, RD=1, WR=0, A1=1, A0=0

🔹 B. CS=0, RD=0, WR=1, A1=1, A0=0

🔹 C. CS=1, RD=1, WR=0, A1=0, A0=1

🔹 D. CS=0, RD=1, WR=1, A1=1, A0=1

💡 Difficulty: medium | ✅ Correct: A

Q3. During a DMA setup, the CPU needs to write a mode word to configure counter 1 as a rate generator. Which pins are involved in this operation and what must be the state of the WR line?

🔹 A. CS low, WR low, A1=0, A0=1

🔹 B. CS low, WR high, A1=0, A0=1

🔹 C. CS high, WR low, A1=1, A0=0

🔹 D. CS low, WR low, A1=1, A0=1

💡 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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