300+ TOP MPMC LAB VIVA Questions and Answers

MPMC LAB VIVA Questions :-

1.What is a Microprocessor?
It is a CPU fabricated on a single chip, program-controlled device, which fetches the instructions from memory, decodes and executes the instructions.

2. Define bit, byte and word.
Bit is either 0 or 1.
Byte is group of 8 bits.
Word is group of 16 bits.

3.What are the different functional units in 8086?
2 units-Bus Interface Unit (BIU) and Execution unit (EU)

4. What is the function of BIU ?
It is used to generate the 20-bit physical address and is responsible for performing all external bus operations.

5. What is the function of EU?
Execution Unit receives program codes and data from BIU, executes these instructions and store the result.

6. What is the maximum size of segment in 8086 microprocessor?
64KB.

7. What is general purpose registers in 8086?
There are 4 general purpose registers are there.

1. AX-ACCUMULATOR
2. BX- BASE
3. CX- COUNT
4. DX-DATA (Extended accumulator)

8. What are the functions of General purpose Registers?

• AX register as 16-bit accumulator, stores all arithmetic and logical operation’s results.
• BX register is used as an offset address Storage.
• CX register is used as counter. Especially used in loop, shift, rotate instructions.
• DX register is used in port operations (IN and OUT)

9. What is special purpose registers in 8086?
CS- CODE SEGMENT
DS-DATA SEGMENT
ES-EXTRA SEGMENT
SS-STACK SEGMENT
BP-BASE POINTER
IP-INSTRUCTION POINTER
SP- STACK POINTER
SI-SOURCE INDEX
DI-DESTINATION INDEX
FLAG REGISTER

10. What are the functions of base Registers?
CS stores program code,
DS stores data
ES sores extra data
SS stores stack data.

11. Name the pin in 8086 microprocessor that is used for selecting mode of operation?
29th pin-MN/MX’
If MN/MX’=0 then maximum mode is selected.
MN/MX’=1 then minimum mode is selected.

12. What is Segment address in 8086?
The part of the segment starting address stored in a segment register is called the segment address.

13. What are the flags in 8086?
In 8086, 9 flags are there. Out of 9, 6 are conditional (status) flags and 3 control flags.
Conditional (status) flags:
Carry flag (CF), Parity flag (PF), Auxiliary carry flag (CF), Zero flag (ZF), Overflow flag (OF), and Sign flag(SF)
Control flags:
Trap flag (TF), Direction flag (DF), Interrupt flag (IF),

14. What is Tri-state logic?
Three Logic Levels are used and they are High (logic 1), Low(logic 0), High impedance(Z) state. The high and low are normal logic levels & high impedance state is electrical open circuit conditions.

15. What is system bus?
Group of address, data and control buses.
Address bus: carry the Address to the memory to fetch either Instruction or Data.
Data bus: carry the Data from the memory.
Control bus: carry the Control signals like RD/WR, reset, ready etc.

16. What is the difference between Maskable interrupts and Non-Maskable interrupts?
An interrupt that can be turned off by the programmer is known as Maskable interrupt.
An interrupt which can be never be turned off (i.e. disabled) is known as Non-Maskable interrupt.

17. What are the different types of Addressing Modes?
There are 12 different types of Addressing Modes. They are:-

1. Immediate:- The Immediate data is a part of instruction.
2. Direct:- A 16-bit memory address (offset) is directly specified in the instruction as a part of it.
3. Register:- Data is stored in a register.
4. Register Indirect:- The address of the memory location which contains data or operand is determined in an indirect way.
5. Indexed:- offset of the operand is stored in one of the index registers.
6. Register Relative:- The data is available at an effective address formed by adding an 8-bit or 16-bit displacement with the content of any one of the registers BX,BP,SI and DI in the default (either DS or ES) segment.
7. Based Indexed:- The effective address of the data is formed, in this addressing mode,by adding content of a base register to the content of an index register.
8. Relative Based Indexed:-  The effective address is formed by adding an 8 or 16-bit displacement with the sum of contents of any one of the base registers and any one of the index registers, in the default segment.
9. Intrasegment Direct Mode:- In this mode, the address to which the control is to bve transferred lies in the segment in which the control transfer instruction lies and appears directly in the instruction as an immediate displacement value.
10. Intrasegment Indirect Mode:- In this mode, the displacement to which the control is to be transferred, is in the same segment in which the control transfer instruction lies, but it is passed to the instruction indirectly.
11. Intersegment Direct:- In this mode, the address to which the control is to be transferred is in a different segment.
12. Intersegment Indirect:- In this mode, the address to which the control is to be transferred lies in a different segment and it is passed to the instruction indirectly sequentially.

18. What is baud rate?
The baud rate is the rate at which the serial data are transmitted. Units- symbols per second.

19. What is a port?
The port is a buffered I/O, which is used to hold the data transmitted from the processor to I/O device or vice-versa.

20. What is 8255?
It is PPI- Programmable Peripheral Interface. it is used to connect I/O devices to microprocessor and supports parallel communication.

21.What are Flag registers?

22.Write the flags of 8086?

23. What are the interrupts of 8086?

24. How clock signal is generated in 8086? What is the maximum internal clock frequency of 8086?

25. Write the special functions carried by the general purpose registers of 8086?

26.What is the need for Port?

27.What is a port?

28.What is processor cycle (Machine cycle)?

29.What is Instruction cycle?

30.What is fetch and execute cycle?

31. In how many ways computer soft wares are categorized?
32. Explain the two types of software?
33. What is an editor?
34. What is an OS and what are its functions?
35. What are the different types of assemblers used?
36. What is a linker?
37. What is a locator?
38. What is coprocessor?
39. What is a coprocessor trap?
40. What is a debugger?
41. In how many groups can the signals of 8085 be classified?
42. What is meant by the statement that 8085 is a 8 bit microprocessor?
43. What is the operating frequency of 8085?
44. What is the purpose of CLK signals of 8085?
45. What are the widths of data bus (DB) and address bus (AB) of 8085?
46. What is the distinguishing feature of DB and AB?
47. The address capability of 8085 is 64 KB.Explain?
48. Does 8085 have serial I/O control?
49. Mention the addressing modes of 8085?
50. What jobs ALU of 8085 can perform?
51. How many hardware interrupts 8085 supports?
52. How many I/O ports can 8085 access?
53. Why the lower byte address bus(A0-A7) and data bus (D0-D7) are multiplexed?
54. List the various registers of 8085?
55. Describe the accumulator register of 8085?
56. What are the temporary registers of 8085?
57. Describe the general purpose registers of 8085?
58. Which are sixteen bit registers of 8085?
59. Discuss PC and SP?
60. Describe the instruction register of 8085?
61. Describe the (status) flag register of 8085?
62. What is the function of ALE and how does it works?
63. Explain the functions of the two DMA signals HOLD and HLDA?
64. Discuss 3 states signals IO/M,S0,S1?
65. What happens when RESET IN(LOW) signal goes low?
66. Function of RESET OUT signal.
67. Indicate different machine cycles of 8085?
68. Name the special purpose registers?
69. Does ALU have any storage facility?
70. Explain XTHL,DAA,RC instructions.
71. What is the difference between JMP and CALL?
72. What happens when CALL instruction is executed?
73. Mention interrupts pins of 8085?
74. Explain maskable and non maskable interrupts?
75. Which is non maskable interrupt for 8085?
76. Do the interrupts of 8085 have priority?
77. What is meant by priority of interrupt?
78. Mention the types of interrupts that 8085 supports?
79. What is the software interrupts of 8085?
80. Explain the software instruction EI and DI?
81. Explain SIM and RIM instructions?
82. What is polling?
83. What is stack?
84. Why stack is used in program?
85. How the stack is initialized?
86. What the SP register does in a program?
87. Comment the size of stack?
88. What type of memory is the stack?
89. What are the software instructions related to stack operations?
90. What are the typical errors associated with using stack in a program?
91. What is a subroutine?
92. Why subroutine used in programs?
93. How subroutine can be called from the main program and how the program returns from the subroutine?
94. Byte wise what are the lengths of CALL and RET instructions?
95. Explain SPHL instruction?
96. Which are the different data transfer schemes?
97. Mention the types of programmed data transfer?
98. Explain DMA?
99. What is meant by address space? what is meant by address space partitioning?
100.Explain memory mapped I/O and I/O mapped I/O schemes?