Sunday, June 22, 2014

MP and MC VIVA QUESTIONS


Microprocessor Questions with Answers

1.What is a Microprocessor?

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

2. What is Instruction Set?
 It is the set of the instructions that the Microprocessor can execute.

3. What is Bandwidth ?
 The number of bits processed by the processor in a single instruction.

4. What is Clock Speed ?
Clock speed is measured in the MHz and it determines that how many instructions a processor can processed. The speed of the microprocessor is measured in the MHz or GHz. 

5. Difference between JMP and JNC?

A:-JMP is Unconditional Branch.      JNC is Conditional Branch.

6. What is Logical Address:?
     
           A memory address on the 8086 consists of two numbers, usually written in hexadecimal and separated by a colon, representing the segment and the offset. This combination of segment and offset is referred to as a logical address
          Logical address=segment: offset

7. What is The Effective Address:
         In general, memory accesses take the form of the following example:
         Mov ax, [baseReg + indexReg + constant]
         This example copies a word sized value into the register AX.                                
         Combined, the three parameters in brackets determine what is called the effective address, which is simply the offset referenced by the instruction

8. What is Physical Address?

Physical memory address pointed by SEGMENT:OFFSET pair is calculated as:

Physical address = (<Segment Addr> * 10) + <Offset Addr>

9.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.

10.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.

11.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.

12.What happens when HLT instruction is executed in processor?

The Micro Processor enters into Halt-State and the buses are tri-stated.

13.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.

14.What is 1st / 2nd / 3rd / 4th generation processor?

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.

15.Name the processor lines of two major manufacturers?

High-end: Intel - Pentium (II, III, 4), AMD - Athlon. Low-end: Intel - Celeron, AMD - Duron. 64-bit: Intel - Itanium 2, AMD - Opteron.

16.How many bit combinations are there in a byte?
Byte contains 8 combinations of bits.

17.Have you studied buses? What types?
There are three types of buses. Address bus: This is used to carry the Address to the memory to fetch either Instruction or Data.
Data bus : This is used to carry the Data from the memory.
Control bus : This is used to carry the Control signals like RD/WR, Select etc.

18.What is the Maximum clock frequency in 8086?
5 Mhz is the Maximum clock frequency in 8086.

19.What is meant by Maskable interrupts?

An interrupt that can be turned off by the programmer is known as Maskable interrupt.

20.What is Non-Maskable interrupts?
An interrupt which can be never be turned off (ie. disabled) is known as Non-Maskable interrupt

21.What are the different functional units in 8086?
Bus Interface Unit and Execution unit, are the two different functional units in 8086.

22.What are the various segment registers in 8086?
Code, Data, Stack, Extra Segment registers in 8086.

23.What does EU do?

Execution Unit receives program instruction codes and data from BIU, executes these instructions and store the result in general registers.

24.Which Stack is used in 8086? k 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.

25.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.

26.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.

27. What are the 4 Segments?

A:-Code Segment Register {CS}            Data Segment Register {DS}
Extra Segment Register {ES}                  Stack Segment Register{SS}


28.What are the General Data Registers & their uses?

A:- The Registers AX,BX,CX,DX are the general Purpose 16-bit registers.AX register as 16-bit accumulator.BX register is used as an offset Storage.CX register is used as default or implied counter.Dx register is used as an implicit operand or destination in case of a few instructions.


29.What are Segment Registers & their uses?

A:-There are 4 Segment Registers Code Segment(CS),Data Segment(DS),Extra Segment(ES) & Stack Segment(SS) registers.CS is used for addressing memory locationin code.DS is used to points the data.ES refers to a segment which is essentially in another data segment.SS is used fopr addressing stack segment of memory.

30. Explain about Direction Flag?

A:-This is used by string manipulation instructions.
If this flag bit is 0 , the string is processed beginning from the lowest to the highest address,i.e.,.Autoincrement mode. Otherwise,the string is processed from the highest towards the lowest address,i.e.,.Autodecrementing mode.


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