Subject 2018 Question Paper — Government College of Engineering and T…

Instructions

• Attempt five questions in all by selecting at least two questions from each section.
• All questions carry equal marks.

Questions

Section-A

• Q1. (a) Discuss the various operations performed by the microprocessor as listed below : 12 (i) Microprocessor initiated operation (ii) External initiated signals. (b) Illustrate the steps and the timing of data flow when the instruction code 4FH (MOV C, A) stored in location 2050 H is fetched. Draw the block diagram showing the data flow between $\mu\text{P}$ and memory. 8 [20 marks]
• Q2. (a) Explain the following instructions of 8085 $\mu\text{P}$ with relevant examples : 10 (i) DAA (ii) SBB (iii) ORA (iv) POP (v) RAR. (b) Draw the interfacing of I/O using Decoders (3 to 8), tristate buffers and latch. One side of tristate buffer is connected with 8 switches. The other side of 8 bit latch is connected with 8-LED's. Read date from switches and write to LEDs. Write instructions to the process. 10 [20 marks]
• Q3. (a) Write a program to do the following operation in 8085 : 10 (i) Define set of 10 bytes of data at location XX50H. (ii) Check each reading to determine whether it is positive or negative. (iii) Add all positive numbers and reject all negative numbers. Draw the flowchart. (b) Specify the contents of memory location XX74H after execution of the following instructions : 10 (i) LX1H, XX70H (ii) MV1, 05H (iii) MV1 A, 01H STORE : = MOV M, A (iv) 1NR A (v) 1NX H (vi) DCR B JNZ STORE HLT. [20 marks]
• Q4. (a) Calculate the count to obtain a $100\text{ }\mu\text{s}$ loop delay and express the value in Hex. Use system clock frequency. 10 $$\begin{array}{lcc} & \text{MV1B, COUNT} & \text{T-States} \\ \text{LOOP :} & \text{NOP} & 4 \\ & \text{NOP} & 4 \\ & \text{DCR B} & 4 \\ & \text{ONZ loop} & 10/7 \end{array}$$ (b) Answer the following questions with relevant answers : 10 (i) Is there any minimum pulse width for 1NTR signal ? (ii) How long 1NTR signal stay high ? (iii) Can the microprocessor be interrupted again before the completion of the first interrupt service routine ? [20 marks]

Section-B

• Q5. (a) Discuss minimum and maximum mode of 8086 $\mu\text{P}$ and explain each pin in both cases. Draw the circuit diagram too. 12 (b) Explain with a block diagram, the working of 8089 microprocessor. 8 [20 marks]
• Q6. (a) Write the program in 8086 to display message "INDIA is great". 10 (b) Write a program in 8086 to compare two strings of 10 bytes each. If strings are equal, display message "string equal" and if not display "strings not equal". 10 [20 marks]
• Q7. (a) Explain with a neat block diagram, the 8253 programmable timer interval. Write the control word. Write instructions to generate a pulse every $50-\mu\text{s}$ from counter 0. Use post address 80H. 12 (b) Explain the working of 8255 PPI in mode 2 as Bidirectional Data Transfer. 8 [20 marks]
• Q8. (a) Explain the Transmitter and Receiver section of 8251 USART. Draw its control word, command word and status word format. 12 (b) Design an RAM & ROM interfacing with 8086 (use 64 K byte each). Assume data if any. 8 [20 marks]