x86 Interview Questions & Answers

Question 1. What Are The Blocking And Nonblocking Assignments In Verilog And Which Is Preferred In Sequential Circuits?

Answer :

A blocking assignment is one in which the statements are executed sequentially, i.e. first statement is executed and variable is assigned a value then second is executed and so on. A non blocking assignment is one in which statements occurs concurrently. Only nonblocking assignments should be used in sequential circuit.

e.g

initial
begin
a=b; //blocking
c<=a; //nonblocking
d=c; //blocking
end

In this example firstly the value of b is assigned to a and this value is assigned to c only after execution of first statement. The second and the third statements are executed simultaneously, i.e.

value a is assigned to c and previous value if c is assigned to d.

Question 2. Write An Rtl Description For D Latch And D Flip Flop?

Answer :

For D Latch:always@(enable)q<=d;

For D flip flop:always@(posedge clock)q<=d;

Question 3. Design A 2-bit Magnitude Comparator And Write Itsrtl Description Also?

Answer :

and gate

Question 4. It Was Calculated That 75 Men Could Complete A Piece Of Work In 20 Days. When Work Was Scheduled To Commence, It Was Found Necessary To Send 25 Men To Another Project. How Much Longer Will It Take To Complete The Work?

Answer :

30 days.Explanation:Before:One day work = 1 / 20One man?s one day work = 1 / ( 20 * 75)Now:No. f workers = 50One day work = 50 * 1 / ( 20 * 75)The total no. of days required to complete the work = (75 * 20) / 50 = 30.

Question 5. Can Rom Be Used As Stack?

Answer :

ROM cannot be used as stack because it is not possible to write to ROM.

Question 6. What Is Stack?

Answer :

Stack is a portion of RAM used for saving the content of Program Counter and general purpose registers.

LIFO stacks, also known as "push down" stacks, are the conceptually simplest way of saving information in a temporary storage location for such common computer operations as mathematical expression evaluation and recursive subroutine calling.

Question 7. What Is Flag?

Answer :

Flag is a flipflop used to store the information about the status of a processor and the status of the instruction executed most recently A software or hardware mark that signals a particular condition or status. A flag is like a switch that can be either on or off. The flag is said to be set when it is turned on.

Question 8. Which Processor Structure Is Pipelined?

Answer :

All x86 processors have pipelined structure.

Question 9. Explain Compiler?

Answer :

Compiler is used to translate the highlevel language program into machine code at a time. It doesn't require special instruction to store in a memory, it stores automatically. The Execution time is less compared to Interpreter.

A compiler is a program that translates a source program written in some highlevel programming language (such as Java) into machine code for some computer architecture (such as the Intel Pentium architecture).

Question 10. Differentiate Between Ram And Rom?

Answer :

RAM: Read / Write memory, High Speed, Volatile Memory. ROM: Read only memory, Low Speed, Non Voliate Memory.

Question 11. Which Transistor Is Used In Each Cell Of Eprom?

Answer :

Floating gate Avalanche Injection MOS (FAMOS) transistor is used in each cell of EPROM.

Question 12. What Is Called Scratch Pad Of Computer?

Answer :

Cache Memory is scratch pad of computer.

Question 13. What Is Cache Memory?

Answer :

Cache memory is a small highspeed memory. It is used for temporary storage of data & information between the main memory and the CPU (center processing unit). The cache memory is only in RAM.

Cache memory is random access memory (RAM) that a computer microprocessor can access more quickly than it can access regular RAM. As the microprocessor processes data, it looks first in the cache memory and if it finds the data there.

Question 14. What Is Interrupt?

Answer :

Interrupt is a signal send by external device to the processor so as to request the processor to perform a particular work.

A signal informing a program that an event has occurred. When a program receives an interrupt signal, it takes a specified action (which can be to ignore the signal).

Question 15. Difference Between Static And Dynamic Ram?

Answer :

Static RAM: No refreshing, 6 to 8 MOS transistors are required to form one memory cell, Information stored as voltage level in a flip flop. Dynamic RAM: Refreshed periodically, 3 to 4 transistors are required to form one memory cell, Information is stored as a charge in the gate to substrate capacitance.

Question 16. What Is Difference Between Primary & Secondary Storage Device?

Answer :

In primary storage device the storage capacity is limited. It has a volatile memory. In secondary storage device the storage capacity is larger. It is a nonvolatile memory. Primary devices are: RAM / ROM. Secondary devices are: Floppy disc / Hard disk.

Question 17. What Are The Static And Dynamic Hazards In Logic Circuits?

Answer :

If for a short period of time circuits goes to some different logic level then it is supposed to have then it is called static hazard.e.g. If the final logic value of output of a given circuit becomes one even if it is supposed to be zero then it is called Static0 Hazard and vice versa. Dynamic Hazard is the one in which the circuit output goes to some other logic level more than once then finally settling down to some appropriate level.

Question 18. What Is Meant By Latch?

Answer :

Latch is a Dtype flipflop used as a temporary storage device controlled by a timing signal, which can store 0 or 1. The primary function of a Latch is data storage. It is used in output devices such as LED, to hold the data for display.

Question 19. What Is The Difference Between Microprocessor And Microcontroller?

Answer :

In Microprocessor more opcodes, few bit handling instructions. But in Microcontroller: fewer opcodes, more bit handling Instructions, and also it is defined as a device that includes micro processor, memory, & input / output signal lines on a single chip.

the basic architectural difference is that microcontroller has an programmable memory while it is not the case with microprocessors.

Question 20. What Is The Disadvantage Of Microprocessor?

Answer :

It has limitations on the size of data. Most Microprocessor does not support floatingpoint operations.

Question 21. Is The Data Bus Is Bi-directional?

Answer :

The data bus is Bidirectional because the same bus is used for transfer of data between Micro Processor and memory or input / output devices in both the direction.

Question 22. Is The Address Bus Unidirectional?

Answer :

The address bus is unidirectional because the address information is always given by the Micro Processor to address a memory location of an input / output devices.

Question 23. What Does Microprocessor Speed Depend On?

Answer :

The processing speed depends on DATA BUS WIDTH.

Question 24. Define Hcmos?

Answer :

High-density n-type Complimentary Metal Oxide Silicon field effect transistor.

Question 25. What Is 1st / 2nd / 3rd / 4th Generation Processor?

Answer :

The processor made of PMOS / NMOS / HMOS / HCMOS technology is called 1st / 2nd / 3rd / 4th generation processor, and it is made up of 4 / 8 / 16 / 32 bits.

Question 26. Why 8085 Processor Is Called An 8 Bit Processor?

Answer :

Because 8085 processor has 8 bit ALU (Arithmetic Logic Review). Similarly 8086 processor has 16 bit ALU.

Question 27. Give Examples For 8 / 16 / 32 Bit Microprocessor?

Answer :

8-bit Processor - 8085 / Z80 / 6800;

16-bit Processor - 8086 / 68000 / Z8000;

32-bit Processor - 80386 / 80486

Question 28. What Are Level-triggering Interrupt?

Answer :

RST 6.5 & RST 5.5 are leveltriggering interrupts.