Microprocessors Viva Questions.

Hey there! Welcome to another informative post on geekstocode! Today we will be looking into Digital Communications Viva Questions on Microprocessors. This will help you with your interviews and even Lab viva exams. Thus, going through this will boost your knowledge about the topic.

This post will cover questions on Microprocessors and Digital Communications. Also, it will have all the important concepts you need to study in this topic.   

Therefore, without any further ado, let’s get started!

Microprocessors Viva Questions. 

1.What is a Microprocessor?

We define a microprocessor as a CPU fabricated on a single chip. Hence, it is a program governed device. And it fetches the instructions from memory, decodes them. Thus, executes the instructions. 

2. What is Instruction Set?

Instruction set is the set of instructions that the Microprocessor can execute.

3. What is Bandwidth ?

Number of bits that the processor processes in a single instruction. 

4. What is Clock Speed ?

The measure of the number of instructions that a processor can process is the clock speed. Also, it is measured in the MHz.

5. What are the features of Intel 8086 ?

The features of Intel 8086 include:

  • Intel released it in 1978.
  • They produced it from 1978 to 1990s
  • A 16-bit microprocessor chip.
  • CPU clock rate:5 MHz to 10 MHz
  • Instruction set:  x86-16
  • Package: 40 pin DIP
  • 16-bit Arithmetic Logic Unit
  • 16-bit data bus  (8088 has 8-bit data bus)
  • 20-bit address bus – 220 = 1,048,576 = 1 meg
  • The address refers to a byte in memory.

6. What is Logical Address:?

We represent a memory address of the 8086 by two numbers, usually written in hexadecimal and separated by a colon, representing the segment and the offset. Thus, we refer this combination of segment and offset as a logical address.

7. What is The Effective Address:

We represent the effective address by the combination of three parameters. i.e the baseReg, indexReg and constant. This is nothing but the offset that the instruction references. 

8. Why is crystal a preferred clock source?

 Crystal is used as a clock source most of the time because of high stability, large Q (Quality Factor) & the frequency that doesn’t drift with aging.

9. What is Tri-state logic?

The tri-state logic is a logic level which has a third line in addition to the high and low logic levels. Also, it is called the enable line. 

10.What happens when  we execute HLT instruction in a processor?

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

11. What is Program counter?

Program counter holds the address of either the first byte of the next instruction which the system fetches for execution or the address of the next byte of a multi byte instruction, which it has not completely fetched. Additionally, 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.

12. What is the 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.

13 . 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.

14. How many bit combinations are there in a byte?

Byte contains 8 combinations of bits.

15. What type of buses have you studied?

I have studied three types of buses. 

The first is the address bus which we use to carry the Address to the memory to fetch either Instruction or Data.

Next is the data bus which we use to carry the Data from the memory.

And the control bus which we use to carry the Control signals like RD/WR, Select etc.

16. What is the Maximum clock frequency in 8086?

5 Mhz is the Maximum clock frequency in 8086.

17. Can you say something about Segment Registers and their uses?

The four segment registers are :

Code Segment (CS) : We use this for addressing memory location in the code

Data Segment(DS) : We use this for data pointing.

Extra Segment(ES) : It refers to the segment which is in other data segment.

And, Stack Segment(SS) : We use this for addressing stack segment of memory. 

18. Can you tell me what are interrupts?

Interrupt is an operation that suspends execution of a program. Thus, it allows the system to take any special action. Also, the interrupt routine executes and normally returns control to the interrupted procedure. Then, this procedure resumes execution. BIOS handles Int 00H-1FH, whereas DOS handles INT 20H-3FH.

19. What is an Opcode?

Op code or the Operation code is the part of the instruction that specifies the operation that the system performs. 

20. What is an Operand?

We refer the data on which the operation is performed as an Operand.

21. Differentiate between “Shift” and “Rotate”.

We use the shift and rotate commands to convert a number to another form where some we shift and rotate bits. 

We can take a rotate instruction to be a closed loop instruction. In other words, in a rotate instruction the data moved out at one end is put back in at the other end.

Whereas, the shift instruction loses the data that is moved out of the last bit locations.

Basic difference between shift and rotate is shift command makes “fall of ” bits at the end of the register.

Where rotate command makes “wrap around” at the end of the register.

22. What is the primary use of a ready pin?

The microprocessor uses READY to check whether a peripheral is ready to accept or transfer data. We can consider a peripheral as a LCD display or analog to digital converter, etc.

And, the ready pin connects these peripherals to the microprocessor.

If READY is high then the periphery is ready for data transfer. If not, then the microprocessor waits until READY goes high.

23. Tell me something about Direction Flag?

The string manipulation instructions use the direction flag. If the flag bit is 0 then, the system processes the string beginning from the lowest to the highest address i.e, Auto Increment mode.

Otherwise, the system processes the string from the highest towards the lowest address,i.e.,.Auto Incrementing mode.

What are the basic units of a microprocessor ?

ALU which is an array of registers and control units are the basic units or blocks of a microprocessor.

24. What can you say about Hardware and Software?

The Software is a set of instructions or commands which the programmable device or a computing machine needs for performing a specific task.

We can define the hardware as the components or devices that the developers use to form a computing machine. Also, we run and test the softwares in the hardwares. However, without software the Hardware is an idle machine.

25. What is assembly language?

Assembly language is a language which uses the mnemonics (short -hand form of instructions)  to write a program. The manufacturers of microprocessors give the mnemonics.


Today we have covered Viva questions on Microprocessors. Make sure to go through all these important questions. Therefore, in this way you can cover all the important topics in the subject. 

Also, we would love to hear your views for the posts. Hope you check out other articles like these which will help you learn important concepts and questions. Also read Compiler design viva questions.

See you in our next post!

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