Started by ganeshbala, Jul 05, 2008, 09:23 PM

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1. Differentiate between memory mapped I/O and I/O mapped I/O.

2. Classify the different groups of 8085 instruction set with example.

3. Differentiate between unidirectional buffer and bi-directional buffer.

4. What is the need for ALE signal in 8085 microprocessor?

5. Give the operation of the foll instructions:(a) DAA (b) DEC.

6. State the functions for ALE and TRAP pins in 8085.

7. If the frequency of the crystal connected to 8085 is 6MHz, calculate the time to fetch and executed NOP instruction.

8. What is a MPU?

9. What do you mean by multiplexing the bus?

10. List out the two parts of an instruction.

11. What is a program counter?

12. What is an instruction?

13. What is PSW?

14. Define - Interrupt.

15. What are the addressing modes for 8085 microprocessor?

16. Where the READY signal used?

17. Define stack.

18. Specify how a program counter is useful in program execution.

19. How the data and address lines are demultiplexed?

20. Show the bit positions of various flags in 8085 flag register?

21. List the various machine cycles of 8085.

22. What is the instruction format of 8085.

23. What are the similarity and difference between subtract and compare instructions?

24. List the type of signals that have to be applied to initiate hardware interrupts in 8085.

25. Write a subroutine to clear the flag register and accumulator?

26. Draw a simple circuit to decode three controls signals RD, WR, IO/M and to produce separate read/write control signal for memory and I/O device?

27. List out the similarities between CALL_RET and PUSH_POP instructions.

28. List four interrupts of 8085.

29. Give the clock out frequency and state time T of 8085 when the crystal frequencies are:

      (a) 5 MHz (b) 6.144 MHz

30. How many times the given loop will be executed? What will be the contents of HL pair when the program control reaches to HLT instruction?

MVI A, 00h

LX1H, 5003H

Loop: DCX H


JNZ loop


31. Define: (a) Instruction Cycle (b) M/c cycle (c) T-state.

32. Explain the execution of the instruction CMA M in 8085.

34. If the program counter is always one count ahead of the memory locations from which the machine code is being fetched, how does the microprocessor change the sequence of program execution with a "Jump" execution?

35. Differentiate between hardware interrupts and software interrupts of 8085.

36. What is DAD and what are the flags, affected by this instructions?

37. What is the function performed by SIM Instruction?

38. What is meant by processor cycle?

39. What are the different memory mapping schemes? Give any one advantage and disadvantage for each

40. Write an 8085 assembly language program, which checks to see if the number is even or odd returns a '0' in B register else returns a '1'.


1.   (i) Draw the pin configuration of 8085 and explain the functional usage of each pin in details.

      (ii) Write a 8085 program to generate a delay of 0.6 sec for the given crystal frequency of 5 MHz.

2.   (i) Explain hardware interrupts in 8085.

      (ii) Draw the timing diagram for MVI A, 30H instruction.

      (iii) What do you mean by polling in 8085.

3.   Write a 8085 assembly language program to generate a delay of 0.1 sec for the given crystal frequency of 2 MHz.

4.   (i) With suitable examples, explain the addressing modes of 8085.

5.   (i) Draw the timing diagram of I/O read cycle in 8085 and explain it.

      (ii) Interface a 8-bit DIP switch with 8085 such that the address assigned to it is FFH.

6.   Explain the 8085 architecture.

7.   Write a 8085 program to convert a binary number to decimal.

8.   (i) Write a 8085 program for multiplying two 8 bit numbers.

      (ii) Write an assembly language program to evaluate the expression (A+(B*C))/D, where A, B, C and D are single byte integer.

9.   (i) Draw the timing diagram of opcode and memory write machine cycles of 8085 for following instructions: MOV V, M; MVI D, data; IN OL; OUT 01; LDA 8000; RST7

      (ii) What is the data transfer instruction? Give example.

10. Write an assembly language program based on 8085 microprocessor to implement a look-up table translation to generate the codes for seven-segment display with our digits. (Assume INPUT PORT O D 6 H, and OUTPUT PORT OD 4H)

11. (i) Write an 8085 assembly language program to perform 32 bit binary addition.

      (ii) What will be the value in ACC, for the given 8085 program below:

      MVI C, 7F

      MVI B, 3E

      MOV A,B



      ANI 7F


12. (i) Write an 8085 assembly language program to fill a block of 1000H bytes starting at address 9000H with characters 2BH.

      (ii) Indicate the logic levels on each control or status pin as logic '0' or logic '1' for 8085 microprocessor with the given data below;

Machine cycle






Memory write

Memory read

I/O read

I/O write

O/P code fetch





14. With example explain different groups of instruction sets.

15. (i) Analysis the program and find the content of A register after execution.

       MVI A, 07


       MOV B,A




       ORA B

      (ii) Explain 8085 interrupts in detail.

16. (i) Draw and explain the timing diagram for STA 4500 instruction.

      (ii) Write as assembly language program to find the average of N numbers.

17. Interface 3 numbers of 8KB EPROM and 5 numbers of 8KB RAM to microprocessor 8085 to have a total memory capacity of 64 KB.

18. (i) Write an assemble language program to add two 2-digit BCD numbers.

19. Write notes on status flag.

20. Write an assembly language program to find the biggest and smallest in an array of given numbers.

21. Write a program to count continuously in hexadecimal from FFB to 00H in a system with a 0.5 micro sec clock period. Use register C to set up a one milli second delay between each count and display the number at one of the output ports.

22. (i) Draw a flowchart and 8085 assembly language program for adding the two hexadecimal numbers 9BH and A7H in register D and E respectively,. If the sum is greater than FFH, display 01H at output PORT0: otherwise, display the sum.

      (ii) Draw the timing diagram for IN and OUT instructions.

23. Explain with the help of suitable diagram how the INTR pin can be used to interrupt the 8085  and how it responds to the signal.

24. (i) Explain the logic instructions of 8085 microprocessor with examples.

     (ii) Write and ALP using 8085 instruction set to add two n-byte numbers stored at memory locations starting at 'X' and 'Y' respectively. Store the result and memory location starting from 'Z'. Draw the flow chart.

25. (i) List all the control signals of the Timing and Control Unit. Explain the sue of each of these signals.

     (ii) Write an ALP to evaluate the expression C = A2 + B2

26. (i) What are the features of FIFO and LIFO memory structures?

27. Draw and explain the timing diagram for the execution of the instruction LDA 2080H.

28. (i) How do you classify the 8085 interrupts what are they? How is the interrupt branch address obtain in each case?

     (ii) Draw the timing diagram of DCX instruction.

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