Computer Architecture Question Bank

1.What is cache memory?                     
The small and fast RAM units are called as caches. When the execution of an instruction calls for data located in the main memory, the data are fetched and a copy is placed in the cache. Later if the same data is required it is read directly from the cache.

2. What is the function of ALU?
Most of the computer operations (arithmetic and logic) are performed in ALU.The data required for the operation is brought by the processor and the operation is performed by the ALU.

3. What is the function of CU?
The control unit acts as the nerve center, that coordinates all the computer operations. It issues timing signals that governs the data transfer.

4. What are basic operations of a computer?
The basic operations are READ and WRITE.

5. What are the registers generally contained in the processor?
MAR-Memory Address Register
MDR-Memory Data Register
IR-Instruction Register
R0-Rn-General purpose Registers
PC-Program Counter

6. What are the steps in executing a program?
1.Fetch
2.Decode
3.Execute
4.Store
 

7. Define interrupt and ISR?
An interrupt is a request from an I/O device for service by the processor. The processor provides the requested service by executing the interrupt service routine.

8. Define Bus?
A group of lines that serves as a connecting path for several devices is called a bus.

9. What is the use of buffer register?
The buffer register is used to avoid speed mismatch between the I/O device and the processor.

10. Compare single bus structure and multiple bus structure?
A system that contains only one bus(i.e only one transfer at a time) is called as a single bus structure. A system is called as multiple bus structure if it contains multiple buses.

11. What is a compiler?
A system software program called a compiler translates the high-level language program into a suitable machine language program containing instructions such as the Add and Load instructions.

12. What is System Software? Give an example?
It is a collection of programs that are executed as needed to perform functions such as

• Receiving and interpreting user commands
• Entering and editing application programs and storing them as files in secondary storage devices.     Ex: Assembler, Linker, Compiler etc

13.What is Application Software? Give an example?
Application programs are usually written in a high-level programming language, in which the programmer specifies mathematical or text-processing operations. These operations are described in a format that is independent of the particular computer used to
execute the program.
Ex: C, C++, JAVA

14. What is text editor?
It is used for entering and editing application programs. The user of this program interactively executes command that allow statements of a source program entered at a keyboard to be accumulated in a file.


15. Discuss about OS as system software?
OS is a large program,or actually a collection of routines,that is used to control the sharing of and interaction among various computer units as they execute application programs.The OS routines perform the tasks required to assign computer resources to individual application programs.

16. What is multiprogrraming or multitasking?

The operating system manages the concurrent execution of several application programs to make the best possible uses of computer resources.this pattern of concurrent execution is called multiprogrraming or multitasking.

17.What is elapsed time of computer system?
The total time to execute the total program is called elapsed time.it is affected by the speed of the processor,the disk and the printer.

18. What is processor time of a program?
The periods during which the processor is active is called processor time of a programIt depends on the hardware involved in the execution of individual machine instructions.

19. Define clock rate?
The clock rate is given by,
                        R=1/P,where P is the length of one clock cycle.

20. Write down the basic performance equation?
T=N*S/R
T=processor time
N=no of instructions
S=no of steps
R=clock rate


21.What is pipelining?
The overlapping of execution of successive instructions is called pipelining.
 
22. What is byte addressable memory?
The assignment of successive addresses to successive byte locations in the memory is called byte addressable memory.

23. What is big endian and little endian format?
The name big endian is used when lower byte addresses are used for the more significiant of the word. The name little endian is used for the less significiant bytes of the word.

24. What is a branch instruction?
Branch instruction is a type of instruction which loads a new value into the program counter.

25. What is branch target?
As a result of branch instructions , the processor fetches and executes the instruction at a new address called branch target, instead of the instruction at the location that follows the branch instruction in sequential address order.

26.What are condition code flags?
The processor keep track of information about the results of various operations for use by subsequent conditional branch instructions. This is accomplished by recording the required information in individual bits, often called condition code flags.

27.Define addressing mode.
The different ways in which the location of an operand is specified in an instruction are referred to as addressing modes.

28.Define various addressing modes.
The various addressing modes are
1.Absolute addressing mode
2.Register addressing mode
3.Indirect addressing mode
4.Index addressing mode
5.Immediate addressing mode
6.Relative addressing mode
7.Autoincrement addressing mode
8.Autodecrement addressing mode

29. What is a pointer?
The register or memory location that contains the address of an operand is called a pointer.

30.What is index register?
In index mode the effective address of the operand is generated by adding a constant value to the contents of a register. The register used may be either a special register or may be any one of a set of general purpose registers in the processor. This register is referred to as an index register.

31.What is assembly language?
A complete set of symbolic names and rules for the use of machines constitute a programming language, generally referred to as an assembly language.

32.What is assembler directive?
SUM EQU 200
Assembler directives are not instructions that will be executed .It simply informs the assembler that the name SUM should be replaced by the value 200 wherever it appears in the program, such statements are called as assembler directives.

33.What is loader ?
Loader is a system software which contains a set of utility programs. It will load the object program to the memory.

34.Define device interface.
The buffer registers DATAIN and DATAOUT and the status flags SIN and SOUT are part of circuitry commonly known as a device interface.

35. What are the basic functional units of a computer?
Input ,memory,arithmetic and logic unit,output and control units are the basic functional units of a computer

36. Define Response time and Throughput.
Response time is the time between the start and the completion of the event. Also referred to as execution time or latency.Throughput is the total amount of work done in a given amount of time

37. Suppose that we are considering an enhancement to the processor of a server system used for web serving.The new CPU is 10 times faster on computation in the web serving application than the original processor. Assuming that the original CPU is busy with computation 40% of the time and is waiting for I/O 60% of the time. What is the overall speedup gained by incorporating the enhancement?

Fractionenhanced = 0.4
Speedupenhanced = 10
Speedupoverall = 1/(0.6+0.4/10) =1/0.64 = 1.56

38. Explain the different types of locality.
Temporal locality, states that recently accessed items are likely to be accessed in the near future.Spatial locality, says that items whose addresses are near one another tend to be referenced close together in time.

PART B

 1.Explain the various addressing modes.

• Register mode
• Absolute mode
• Immediate mode
• Indirect mode
• Indexed mode
• Relative mode
• Auto increment mode
• Auto Decrement mode

2. Discuss the following:
(i) Basic operational concepts of a computer.

• Instructions
• Operational details of a processor
• Registers
• Operating steps

(ii) Basic instruction types.

• Zero address instruction
• One address instruction
• Two address instruction
• Three address instruction

3.Discuss in detail the various measures of performance of a computer

• Processor clock
• Pipelining and super scalar operation
• Clock rate
• Instruction set
• Compiler

4. Explain briefly about the stack and Queue organization.

• Explanation
• Programs

5.Discuss the following:
(i)Instruction execution & straight-line sequencing.

• Execution steps
• Diagram

(ii) Branching.

• Explanation
• Diagram

6. Explain in detail the data transfer between the memory & I/O unit.

• Program controlled I/O
• Flags (SIN, SOUT)
• Buffers (DATAIN, DATAOUT)
• Coding
• Diagram

7.Explain the various functional units of a computer

• Input unit
• Output Unit
• ALU
• CU
• MU

8. Explain the software performance of a computer.

• Explanation

9. Explain the different ways of Bus Structures.

• Input/output devices
• Ports
• Networking. 

16 Marks

Explain the various addressing modes.
• Register mode
• Absolute mode
• Immediate mode
• Indirect mode
• Indexed mode
• Relative mode
• Auto increment mode
• Auto Decrement mode

2. Discuss the following:
(i) Basic operational concepts of a computer.
• Instructions
• Operational details of a processor
• Registers
• Operating steps
(ii) Basic instruction types.
• Zero address instruction
• One address instruction
• Two address instruction
• Three address instruction

3.Discuss in detail the various measures of performance of a computer
• Processor clock
• Pipelining and super scalar operation
• Clock rate
• Instruction set
• Compiler

4. Explain briefly about the stack and Queue organization.
• Explanation
• Programs


5.Discuss the following:
(i)Instruction execution & straight-line sequencing.
• Execution steps
• Diagram
(ii) Branching.
• Explanation
• Diagram


6.Explain the various functional units of a computer
• Input unit
• Output Unit
• ALU
• CU
• MU

7. Explain the software performance of a computer.
• Explanation


8.Explain in detail the principle of Carry look ahead adder?

• Generate function
• Propagate function
• 4-bit carry look-ahead adder

9. Explain the sequential circuit binary multiplier and give an example for it.

• Explanation
• Diagram
 

10. Explain Booth algorithm for signed-operand multiplication.
• Algorithm
• Explanation with example

11. Explain the design of fast adders with neat diagrams.
• Diagram
• Explanation