MICROPROCESSOR INTERVIEW QUESTIONS
1.
How many bits does 8086 microprocessor have?
2. What is the size of data bus in 8086?
3. What is the size of address bus in 8086?
4. What is the max memory addressing capacity of 8086?
5.
Which are the basic parts of 8086?
6. What are the functions of BIU?
7.
What are the functions of EU?
8. How many pin IC 8086 is?
9. What IC8086 is?
10. What is the size of instruction queue in 8086?
11. What is the size of instruction queue in 8088?
12. Which are the registers present in 8086?
13. What is pipelining in 8086?
14. How many 16 bit registers are available in 8086?
15. Specify addressing modes for any instruction?
16. What is assembler directives?
17. What .model small stands for?
18. What is the supply requirement of 8086?
19. What is the relation between 8086 processor frequency & crystal frequency?
20. Functions of Accumulator or AX register?
21. Functions of BX register?
22. Functions of CX register?
23. Functions of DX register?
24. How Physical address is generated?
25. Which are pointers present in this 8086?
26. Which is by default pointer for CS/ES?
27. How many segments present in it?
28. What is the size of each segment?
29. Basic difference between 8085 and 8086?
30. Which operations are not available in 8085?
31. What is the difference between min mode and max mode of 8086?
32. What is the difference between near and far procedure?
33. What is the difference between Macro and procedure?
34. What is the difference between instructions RET & IRET?
35. What is the difference between instructions MUL & IMUL?
36. What is the difference between instructions DIV & IDIV?
37. What is difference between shifts and rotate instructions?
38. Which are strings related instructions?
39. Which are addressing modes and their examples in 8086?
40. What does u mean by directives?
41. What does u mean by Prefix?
42. What .model small means?
43. Difference between small, medium, tiny, huge?
44. What is dd, dw, db?
45. Interrupts in 8086 and there function.
46. What is the function of 01h of Int 21h?
47. What is the function of 02h of Int 21h?
48. What is the function of 09h of Int 21h?
49. What is the function of 0Ah of Int 21h?
50. What is the function of 4ch of Int 21h?
51. What is the reset address of 8086?
52. What is the size of flag register in 8086? Explain all.
53. What is the difference between 08H and 01H functions of INT 21H?
54. Which is faster- Reading word size data whose starting address is at even or at odd address of
memory in 8086?
55. Which are the default segment base: offset pairs?
56. Can we use SP as offset address holder with CS?
57. Which are the base registers in 8086?
58. Which is the index registers in 8086?
59. What is segment override prefix?
60. Whether micro reduces memory requirements?
61. What is macro?
62. What is diff between macro and procedure?
63. Types of procedure?
64. What TASM is?
65. What TLINK is?
66. What TD is?
67. What do u mean by assembler?
68. What do u mean by linker?
69. What do u mean by loader?
70. What do u mean by compiler?
71. What do u mean by emulator?
72. Stack related instruction?
73. .stack 100 means?
74. What is 20 dup (0)?
75. Which flags of 8086 are not present in 8085?
76. What is the size of flag register?
77. Can you perform 32 bit operation with 8086? How?
78. Whether 8086 is compatible with Pentium processor?
79. What is 8087? How it is different from 8086?
80. While accepting no. from user why u need to subtract 30 from that?
81. While displaying no. from user why u need to add 30 to that?
82. What are ASCII codes for nos. 0 to F?
83. How does U differentiate between positive and negative numbers?
84. What is range for these numbers?
85. Which no. representation system you have used?
86. What is LEA?
87. What is @data indicates in instruction- MOV ax, @data?
88. What is maximum size of the instruction in 8086?
89. Why we indicate FF as 0FF in program?
90. What is mul BX and div BX? Where result goes?
91. Where queue is present?
92. What is the advantage of using internal registers?
93. What is SI, DI and their functions?
94. Which are the pointers used in 8086 and their functions?
95. What is a type of queue in 8086?
96. What is minimum mode of 8086?
97. What is maximum mode of 8086?
98. Which are string instructions?
99. In string operations which is by default string source pointer?
100.
In string operations which is by default string destination pointer?
101. What are the flags in 8086? - In 8086 Carry flag, Parity flag, Auxiliary carry flag, Zero flag,
Overflow flag, Trace flag, Interrupt flag, Direction flag, and Sign flag.
102.
What are the various interrupts in 8086? - Maskable interrupts, Non-Maskable
interrupts.
103.
What is meant by Maskable interrupts? - An interrupt that can be turned off by the
programmer is known as Maskable interrupt.
104.
What is Non-Maskable interrupts? - An interrupt which can be never be turned off
(ie.disabled) is known as Non-Maskable interrupt.
105.
Which interrupts are generally used for critical events? - Non-Maskable
interrupts are used in critical events. Such as Power failure, Emergency, Shut off etc.,
106.
Give examples for Maskable interrupts? - RST 7.5, RST6.5, RST5.5 are Maskable
interrupts
107.
Give example for Non-Maskable interrupts? - Trap is known as Non-Maskable
interrupts, which is used in emergency condition.
108.
What is the Maximum clock frequency in 8086? - 5 Mhz is the Maximum clock
frequency in 8086.
109.
What are the various segment registers in 8086? - Code, Data, Stack, Extra
Segment registers in 8086.
110. Which Stack is used in 8086? - FIFO (First In First Out) stack is used in 8086.In this type of
Stack the first stored information is retrieved first.
111. What are the address lines for the software interrupts? RST 0 0000 H
RST1 0008 H
RST2 0010 H
RST3 0018 H
RST4 0020 H
RST5 0028 H
RST6 0030 H
RST7 0038 H
112. What is SIM and RIM instructions? - SIM is Set Interrupt Mask. Used to mask the hardware
interrupts. RIM is Read Interrupt Mask. Used to check whether the interrupt is Masked or not.
113. Which is the tool used to connect the user and the computer? - Interpreter is the tool
used to connect the user and the tool.
114. What is the position of the Stack Pointer after the PUSH instruction? - The address
line is 02 less than the earlier value.
115. What is the position of the Stack Pointer after the POP instruction? - The address line
is 02 greater than the earlier value.
116. Logic calculations are done in which type of registers? - Accumulator is the register in
which Arithmetic and Logic calculations are done.
117. What are the different functional units in 8086? - Bus Interface Unit and Execution unit,
are the two different functional units in 8086.
118. Give examples for Micro controller? - Z80, Intel MSC51 &96, Motorola are the best
examples of Microcontroller.
119. What is meant by cross-compiler? - A program runs on one machine and executes on
another is called as cross-compiler.
120.
What are the address lines for the hardware interrupts? -
RST 7.5 003C H
RST 6.5 0034 H
RST 5.5 002C H
TRAP 0024 H
121. Which Segment is used to store interrupt and subroutine return address registers? Stack Segment in segment register is used to store interrupt and subroutine return address
registers.
122.
Which Flags can be set or reset by the programmer and also used to control
the operation of the processor? - Trace Flag, Interrupt Flag, Direction Flag.
123.
What does EU do? - Execution Unit receives program instruction codes and data from
BIU, executes these instructions and store the result in general registers.
124.
Which microprocessor accepts the program written for 8086 without any
changes? - 8088 is that processor.
125.What is the difference between 8086 and 8088? - The BIU in 8088 is 8-bit data bus & 16bit in 8086.Instruction queue is 4 byte long in 8088and 6 byte in 8086.
126.
What are the various registers in 8085? - Accumulator register, Temporary
register, Instruction register, Stack Pointer, Program Counter are the various registers in 8085 .
127. In 8085 name the 16 bit registers? - Stack pointer and Program counter all have 16 bits.
128.
What are the various flags used in 8085? - Sign flag, Zero flag, Auxillary flag, Parity
flag, Carry flag.
129.
What is Stack Pointer? - Stack pointer is a special purpose 16-bit register in the
Microprocessor, which holds the address of the top of the stack.
130.
What is Program counter? - Program counter holds the address of either the first
byte of the next instruction to be fetched for execution or the address of the next byte of a multi
byte instruction, which has not been completely fetched. In both the cases it gets incremented
automatically one by one as the instruction bytes get fetched. Also Program register keeps the
address of the next instruction.
131. Which Stack is used in 8085? - LIFO (Last In First Out) stack is used in 8085.In this type of
Stack the last stored information can be retrieved first.
132.
What happens when HLT instruction is executed in processor? - The Micro
Processor enters into Halt-State and the buses are tri-stated.
133.
What is meant by a bus? - A bus is a group of conducting lines that carriers data,
address, & control signals.
134.
What is Tri-state logic? - Three Logic Levels are used and they are High, Low, High
impedance state. The high and low are normal logic levels & high impedance state is electrical
open circuit conditions. Tri-state logic has a third line called enable line.
135.Give an example of one address microprocessor? - 8085 is a one address microprocessor.
136.
In what way interrupts are classified in 8085? - In 8085 the interrupts are
classified as Hardware and Software interrupts.
137. What are Hardware interrupts? - TRAP, RST7.5, RST6.5, RST5.5, INTR.
138.
What are Software interrupts? - RST0, RST1, RST2, RST3, RST4, RST5, RST6,
RST7.
139.
Which interrupt has the highest priority? - TRAP has the highest priority.
140.
Name 5 different addressing modes? - Immediate, Direct, Register, Register
indirect, Implied addressing modes.
141. How many interrupts are there in 8085? - There are 12 interrupts in 8085.
142.
What is clock frequency for 8085? - 3 MHz is the maximum clock frequency for
8085.
143.
What is the RST for the TRAP? - RST 4.5 is called as TRAP.
144.
In 8085 which is called as High order / Low order Register? - Flag is called as
Low order register & Accumulator is called as High order Register.
145.What are input & output devices? - Keyboards, Floppy disk are the examples of input
devices. Printer, LED / LCD display, CRT Monitor are the examples of output devices.
146.
Can an RC circuit be used as clock source for 8085? - Yes, it can be used, if an
accurate clock frequency is not required. Also, the component cost is low compared to LC or
Crystal.
147. Why crystal is a preferred clock source? - Because of high stability, large Q (Quality Factor)
& the frequency that doesn’t drift with aging. Crystal is used as a clock source most of the times.
148.
Which interrupt is not level-sensitive in 8085? - RST 7.5 is a raising edge-
triggering interrupt.
149.
What does Quality factor mean? - The Quality factor is also defined, as Q. So it is a
number, which reflects the lossness of a circuit. Higher the Q, the lower are the losses.
150.
What are level-triggering interrupt? - RST 6.5 & RST 5.5 are level-triggering
interrupts.
151.