Microprocessor 8085 Question Bank - I

Microprocessor

Short Answer Type Questions

1. List the components of a computer.
2. Explain the function of each component of a computer.
3. What is a Microprocessor? What is the difference between a Microprocessor & CPU?
4. Define bit, byte, word, double word, quad word and instruction
5. What determines that Microprocessor is an 8, 16 or 32 bit?
6. Explain the difference between the machine language and the assembly language of the 8085 microprocessor.
7. What is an assembler?
8. What are low and high level languages?
9. What are the advantages of an assembly language in comparison with high level languages?
10. List the four operations commonly performed by the MPU.
11. Specify the four control signals commonly used by the 8085 MPU.
12. Specify the function of the address bus and the direction of the information flow on the address bus.
13. Why is the data bus bidirectional?
14. What is a bus?
15. How many memory locations can be addressed by a microprocessor with 14 address lines?
16. How many address lines are necessary to address two megabytes (2048K) of memory?
17. Why is the data bus bidirectional?
18. Specify the control signal and the direction of the data flow on the data bus in a memory-write operation.
19. What is the function of the accumulator?
20. What is a flag?
21. Why are the program counter and the stack pointer 16-bit registers?
22. What is the function of the WR signal on the memory chip?
23. Specify the number of registers and memory cells in a 128 x 4 memory chip.
24. What is the memory word size required in an 8085 system?
25. While executing a program, when the 8085 MPU completes the fetching of the machine code located at the memory address 2057H, what is the content of the program counter?
26. What is the role of clock in Microprocessor?
27. Which pins of 8085 carry only data?
28. Which pins of 8085 are bidirectional?
29. Differences between the 8155/8156 and 8355/8755 peripherals.
30. What is the difference between INR & INX instructions?
31. List all the interrupt signals of 8085 microprocessor.
32. Write short note on evolution of microprocessors.
33. Explain the functions of the ALE and IO/M signals of the 8085 microprocessor.
34. List the sequence of events that occurs when the 8085 MPU reads from memory.
35. If the 8085 adds 87H and 79H, specify the contents of the accumulator and the status of the S, Z, and CY flags.
36. If the clock frequency is 5 MHz, how much time is required to execute an instruction of 18 T-states?
37. Discuss the programming model of 8085 μP with the help of suitable diagram.
38. Draw and explain the timing diagram for opcode fetch operation
39. Discuss various types of addressing modes of 8085.
40. Explain why the number of output ports in the peripheral-mapped I/O is restricted to 256 ports.
41. In the peripheral-mapped I/O, can an input port and an output port have the same port address? Explain.
42. What are the control signals necessary in the memory-mapped I/O?
43. List the four categories of 8085 instructions that manipulate data.
44. Define opcode and operand, and specify the opcode and the operand in the instruction MOV H, L.
45. Write logical steps to add the following two Hex numbers. Both the numbers should be saved for future use. Save the sum in the accumulator. Numbers: A2H and 18H.
46. What is the need for ALE signal in microprocessor 8085?
47. How many machine cycles are needed to execute STA 1000h and MVI M, 30h
48. What is the need for interfacing?
49. Compare memory mapped I/O and Peripheral mapped I/O.
50. Differentiate between CALL/RET and PUSH/POP
51. Differentiate between SRAM and DRAM.
52. Differentiate between full decoding and absolute decoding technique.
53. What is memory, Classify the read/write and read only memory
54. State the disadvantages of memory mapped I/O scheme.
55. Differentiate between software and hardware interrupt?
56. What is interrupt? Name the vectored and non vectored interrupts of 8085?
57. What do you mean by timing diagram?
58. Define instruction cycle and machine cycle?
59. Define T – state and in which T cycle the ALE signal is activated?
60. What do you mean by masking the interrupt? How it is activated in 8085 system?
61. Show the different instruction formats used in 8085.
62. What is the type of stack used in 8085?
63. What are the different addressing modes of 8085?
64. Define addressing modes. How many addressing modes are available in 8085?
65. The last executable instruction in a procedure must be ………….. .
66. Explain the following instruction: LHLD 8020,  XTHL
67. What is the subroutine? How it is useful?
68. Explain the need of software timers.
69. If the CALL and RET instructions are not provided in the 8085, could it be possible to write subroutines for this microprocessor? If so how will you call and return from the subroutine?
70. What is the significance of ‘XCHG’ and ‘SPHL’ instructions?
71. Write an initialization program to mask RST 6.5 and disable RST 5.5 and RST 7.5
72. Write an initialization program to disable RST 7.5 and enable RST 5.5 and RST 7.5
73. After the execution of RIM instruction, the contents of the accumulator is found to be 4Ch. Put your comments on the result.