UNIV4VINU | ENGINEERING ACHIEVERS

Answer ALL questions.

PART A — (10 x 2 - 20 marks)

1. Sketch the schematic to generate separate read/write control signals for memory

and I/O related signals in 8085.

2. Calculate the execution time of an instruction MVI A, 82 H in 8085 runs at 2 MHz.

3. Write an assembly language progr am of 8085 to add two numbers stored in

memory locations 4040 H and 4041 H. Save the sum in location 4042 H.

4. Assume register B holds 93 H and the accumulator holds 15 H. Illustrate the

results of the instructions ORA B, XRA B and CMA.

5. Mention some of the applications of Rotate Instructions.

6. Design an 8-key input port with device address FF H using a 3 to 8 decoder to

interface with 8085.

7. How many interrupt sources are available in 8051? What are they?

8. Write short description on register bank registers and their uses.

9. What is called "read-modify-write"?

10. Why do you need a driver in between the microcontroller and the stepper motor?

PART B — (5 x 16 = 80 marks)

11.(a)

(i) Design an interfacing circuit using a 3-to-8 decoder to interface the 2732 EPROM

memory chip (4096 x 8), so that the memory address of this chip ranges from 0000 H

to 0 FFFH. (8)

(ii) Two machine codes 3E H and 32 H are stored in memory locations 2000 H and

2001 H respectively. The first machine code 3E H represents the opcode to load a data

byte in the accumulator and

the second code 32 H represents the data byte to be loaded in the accumulator.

Illustrate and explain the bus timings of 8085 as these machine codes are executed.

(8)

Or

(b) (i)Describe an 8085 interrupt process. (8)

(ii) Write short notes on RST (RESTART) instructions. (8)

12.(a)Write down the comparison of

(i) Memory mapped I/O and peripheral I/O. (8)

(ii) CALL, RET and PUSH, POP instructions. (8)

Or

(b) (i) Sixteen bytes of data are stored in memory locations at XX 50 H to XX 5F H.

Write a program to transfer the entire block of data to new memory locations starting

at XX 70 H. Using 8085 instructions. (8)

(ii) Registers BC contain 8538 H and registers DE contain 62A5 H. Write instructions

to subtract the contents of DE from the contents of BC and place the result in BC. (8)

13.(a) List the elements of the 8255 Programmable Peripheral Interface (PPI) and

explain its various operating modes. (16)

Or

(b) With a block diagram of 8279 keyboard/display controller, explain its function.

(16)

14.(a) (i)Explain how the memory is organized in 8051 family of controller.

(8)

(ii) What are the functional blocks available in 8051? Explain with a block diagram.

(8)

Or

(b) (i) How does the timer operate in 8051 in mode 2? Explain with suitable diagram.

(8)

(ii)Assuming XTAL = 11.0592 MHz, write a 8051 assembly language program to

generate a square wave of 50 Hz frequency on pin P 2.3. (8)

15. (a) (i) How many addressing modes ar e available in 8051? Explain them with

examples. (8)

(ii) Tabulate the program control instructions of 8051 and explain any five of them.

(8)

Or

B.E/B.TECH.DEGREE EXAMINATION, MAY/JUNE 2007.

Fifth Semester

Computer Science and Engineering

CS1304 – MICROPROCESSORS AND MICROCONTROLLERS

(Regulation 2004)

Time: Three hours Maximum: 100 marks

Answer ALL questions

PART A – (10 ´ 2 = 20 marks)

1. How address and data lines are demultiplexed in 8085?

2. What is the function performed by SIM instruction in 8085?

3. What is pipelined architecture?

4. How the interrupts can be masked/unmasked in 8086?

5. What are the signals involved in memory bank selection in 8086

micro processor?

6. How clock signal is generated n 8086? What is the maximum internal clock

frequency of 8086?

7. What is the function of gate signal in 8254 timer?

8. Write the format of KW1 in 8259.

9. List the interrupts of 8051 micro controller.

10. What are register banks in 8051 microcontroller?

PART B – (5 ´ 16 = 80 marks)

11. (a) (i) Explain the various logical and arithmetic instructions available in 8085

microprocessor. (10)

(ii) Explain the function of various flags of 8085 microprocessor (6)

Or

(b) (i) Differentiate between I/O mapped I/O and memory mapped I/O. (6)

(ii) Write an 8085 assembly language program to convert 8 bit binary to

ASCII code. (10)

12. (a) (i) Describe the action taken by 8086 when INTR pin is activated. (6)

(ii) Write an assembly language program in 8086j to search the largest data in

an array. (10)

Or

(b) (i) Discuss the various addressing modes of 80896 microprocessor. (10)