Cpu Interview Questions & Answers

Question 1. Explain The Functions Of The Cu And Alu In The Cpu Of A Computer?

Answer :

The characteristics of the CU or control unit are as follows:

• This part of the of the CPU is the one that is in charge of all the operations being carried out.
• It is responsible to direct the system to execute instructions.
• It helps in communication between the memory and the arithmetic logical unit.
• It also aids in the loading of data and instructions residing in the secondary memory to the main memory as required.

The characteristics of the ALU are as follows:

• The ALU is responsible for performing all logical and arithmetic operations.
• Some of the arithmetic operations are as follows: addition, subtraction, multiplication and division.
• Some of the logical operations are as follows: comparison between numbers, letter and or special characters.
• The ALU is also responsible for the following conditions: Equal-to conditions, Less-than condition and greater than condition.

Question 2. Define The Basic Logical Structure Of A Computer?

Answer :

The basic logical structure of a computer are as follows:

• The BIOS ( basic input output system ) responsible for booting up the computer.
• CPU ( central processing unit ) the brains of the computer executes the processes.
• Memory / RAM ( random access memory ) used to store temporary data.
• Hard Disk is used for the storage of permanent data.
• Input / output devices are used to give input to a computer and derive output from it.
• Communication Channel acts as an interface for external and internal devices.

Question 3. Are There Any Problems That The Cpu Faces? Have Any Measures Been Taken To Make It More Efficient?

Answer :

Although the CPU needs only a few parts to do its job, it has been modified to increase its performance. The enhancements are made in order to process data faster. 

One of the weaknesses of the basic CPU was that it was not doing any processing during the time that it fetches an instruction from the computer memory. 

To reduce this, a memory storage area was created inside the CPU called Cache or  L1 type Cache. The Cache is very fast, and is used to store information that the CPU  needed to access the most. Level 2 Cache was also developed.

Now that the CPU has to wait much less for the data to be processed, the speed at which the data can be processed had to be enhanced. To do this, multiple ALUs  (Arithmetic Logic Unit ) were placed on the CPU, so that many more calculation was done each clock cycle.

In addition, the FPU (Floating Point Unit) was added. The FPU is similar to the ALU, except that it is more advanced. It can handle extremely large and extremely small numbers, allowing greater processing speeds. Also, it can simultaneously process multiple graphics and sounds at a time.

Question 4. What Is Risc Technology?

Answer :

1. RISC stands for Reduced Instruction Set Computing. 
2. It uses a small subset of instructions to carry out processes.
3. As the number of instructions are lesser, the speed of processing is much improved and faster.
4. However, when complex operations are dealt with, they have to be broken down into a series of smaller instructions.

Question 5. What Are The Steps Involved In Following A Particular Instruction Given By The Cpu?

Answer :

The following steps are followed-

• The instruction pointer tells the instruction fetch where in the memory the instruction is.
• The fetch takes the instruction and gives it to the decoder, which determines the steps that are necessary to fulfill the instructions.
• The information is then sent to the ALU, which performs the instructions that need to be performed. This includes adding, subtracting, or manipulating the data further. 
• Finally, the instructions are sent out into the computer where they are needed.

Question 6. What Do You Mean By Parallel Processing?

Answer :

It is a type of processing in which the CPU divides the problem into two parts.

It works as:

1. Each part is sent to separate processors.
2. Each processor has its own memory. They individually solve the given problems and return the result.
3. The CPU assembles the results and hence, the problem is solved.
4. Some computers operate in terms of teraflops or trillions of floating-point instructions per second.

Question 7. What Is Cache Memory?

Answer :

It is a temporary memory storage area which helps to speed up data transfer within a computer. A Microprocessor looks for the data in the Cache memory as the data transferred Cache is much faster. If the data is not found in the cache, the CPU looks for it in the memory.

The following are two types of Cache-

• Internal or Level 1: In this, the Cache is built into the Microprocessor.
• External or Level 2: In this, the Cache is built on a separate chip.

The Internal Cache is the fastest but it is very expensive.

Question 8. What Is System Bus? Explain A Few Related Terms?

Answer :

System Bus are parallel electrical paths that transport data between the CPU and Memory.

Bus Width: The number of electrical paths that to carry the data. It is measured in Bits. With larger Bus Widths, a CPU can transfer more data at a time.

Bus Speed: The speed of the bus is measured in megahertz (MHz), refers to how much data can move across the bus simultaneously. Personal computers have a bus speeds of 400 MHz or 533 MHz.

Question 9. What Do You Mean By Ram?

Answer :

In RAM or Random Access Memory, Data can be accessed randomly.

There are two types of RAM-

Static RAM: It retains its contents with the help of CPU. It is faster and more expensive than Dynamic RAM. It is generally used for Level 2 cache.

Dynamic RAM: It cannot retain its contents if not continuously refreshed by the CPU.

Its types are- 

• Synchronous DRAM: It is the faster type of DRAM, used in modern and more advanced systems.
• Rambus DRAM: It is faster than Synchronous DRAM and is expected to become more commonly used.

Question 10. Explain Some Memory Components?

Answer :

Some of the memory components are:

Semiconductor Memory: It is used by most by most modern computers. It is reliable, inexpensive and compact. However, it requires continuous power supply and data is lost if current is interrupted.

RAM and ROM: They stand for Random Access Memory and Read Only Memory respectively.

Flash Memory: This memory is electrically erasable and reprogrammable.

Question 11. What Do You Understand By The Term ‘transistors’?

Answer :

Transistors are electronic switches that may or may not allow the flow of current in a current path. 

• When it allows current to flow, the switch is ON. This represents 1 bit.
• When it does not allow current to flow, the switch is OFF. This represents 0 bit.
• Transistors are placed into chips also known as IC. They measure in mm`s and are known contain millions of transistors.
• Microprocessors these days are created using microns as their measuring size.

Question 12. What Does A Microprocessor Mean?

Answer :

A Microprocessor is a miniature CPU unit that is etched on a silicon chip. A CPU (Central Processing Unit) hardware which carries out the instructions of a computer system. The Microprocessor unit consists of millions of tiny transistors. It has multi purposes and is programmable. They operate on numbers and symbols represented in Binary Numeral Language.

Question 13. What All Does A Microprocessor Comprise Of?

Answer :

They comprise of the following key components-

Central Processing Unit: It carries out the instructions of a computer system

Registers: They store bits of information in a way that all the bits can be written to or read out simultaneously.

System clock: simple count of the number of ticks that have transpired since some arbitrary starting date, called the Epoch.

Question 14. What Do You Understand By Coding Schemes?

Answer :

Coding schemes are a common way of representing a character of data. It is required in computers for exchanging data. The following are a few common coding schemes-

ASCII: It stands for the American Standard Code for Information Interchange. It is used on almost all computers, hence considered as a standard coding scheme.

EBCDIC: It stands for Extended Binary Coded Decimal Interchange Code. Its is primarily used in IBM and IBM-compatible mainframes.

Unicode: It is designed to accommodate alphabets (- 256). It uses 16 bits to represent one character and requires twice as much space to store data. It can have a maximum of 65,536 possible values.

Question 15. What Do You Understand By System Clock?

Answer :

Some of the characteristics of the system clock are as follows:

• The system clock is used to produce a specific pulse at a fixed rate of time.
• The machine cycle of a system can be completed in a single or multiple clock pulses.
• A single program instruction could be multiple instructions for the cpu.
• Any central processing unit has a predefined set of instructions also known as the instruction set. These are the instructions that it can process and understand.
• The clock speeds are nowadays measures in Ghz. 1ghz = 1000 mhz.

Question 16. What Is System Unit?

Answer :

It is an enclosure that contains most of the components of a computer system such as the Motherboard and other Storage devices.

Motherboard: It is a Flat circuit board that holds the computer circuitry.

Storage devices: These devices are used for long term storage of memory. Some of them are- hard drive, diskette, DVD_ROM, etc.

Question 17. Explain The Characteristics Of Instruction And Execution Time?

Answer :

Some of the characteristics of instruction time are as follows:

• The instruction time is also known as the I-time.
• It is the time taken by the Control Unit to get an instruction from memory and to load it to the register.
• The time also includes the taken by the CU for instruction decoding and to find out the location of the required data.

Some characteristics of execution time are:

It is the time required by the control unit to move data from the memory to the registers in the ALU, the ALU is responsible for the execution of instructions on this data.

Question 18. Mention Briefly The Steps Involved In The Execution Of A Program?

Answer :

The following steps are involved in the execution of a program:

Fetch: The control unit is given an instruction.

Decode: The control unit then decodes the newly received instruction.

Execute: During the execution the Control unit first commands the correct part of hardware to take action. Once that is found out the control is handed over to the hardware. Now the task is performed.

Store: Once the task is saved successfully the end result is stored.

After the cycle is complete the Control unit is again handled the conrol.

Question 19. What Are The Different Ways In Which Data Can Be Represented?

Answer :

There are three ways in which data can be represented namely Bit, Byte and Word:

Bit: This is also the short name for binary digits. By being binary it means that BIT can only have two values zero and one. A characteristic of BIT is that it can never be empty. Zero implies a power off state whereas one means on state.

Byte: A byte is a collection or group of 8 bits. A byte can store a single character which can either be an alphabet, a number or a special character. The byte is generally used to measure the storage capacities.

Word: The number of bits that a cpu possess indicates the power of the computer. It also indicates how many number of bytes are present. In today`s date most computers can handle 32 or 64 bit length.

Question 20. Explain What Do You Understand By Registers, Briefly Explain The Various Types Of Registers?

Answer :

• Registers can be considered to be special purpose memory which reside within the CPU.
• The registers are high speed temporary memory used to help the CPU get access to data and instructions quickly and effectively. There are various type of registers such as Instruction register, Status register and data register.
• The instructions register is responsible for the storage of the of the instructions that are being currently executed.
• The status register is used to keep a tab of the status operations of the arithmetic logical unit.
• The data register is used to store information or data that is to be processed, it is also used to store information or results that have been derived from a process.

Question 21. Briefly Explain The Types Of Data Storage And Its Relation With The Cpu.?

Answer :

There are overall two main types of storage:

Primary Storage ( memory ): This type of storage is primarily used to store information temporarily. The CPU does not directly access the secondary memory, instead it always relies on the primary memory.

Secondary storage: This type of storage is primarily used to store data or long periods. This type of memory is stored in external devices such as hard drives etc.

Any data that resides on a disk or input device cannot be accessed by the CPU directly, it should always reside in the main memory. The control unit accesses the data from the disk memory and places it in the main memory.

The data is present in the primary memory until the program requiring it is executed or is terminated.