IBCS: Computer Organization

Which of the following is a function of the Arithmetic Logic Unit (ALU) in a computer?

• Storing data and instructions

• Performing arithmetic and logic operations on data

• Controlling the flow of data between input and output devices

• Managing the physical addresses of memory cells

Answer explanation

The correct choice is 'Performing arithmetic and logic operations on data' because the ALU is specifically designed to execute mathematical calculations and logical comparisons, which are essential functions in computing.

According to the von Neumann architecture, which component is responsible for holding both data and instructions?

• Arithmetic/Logic Unit

• Control Unit

• Memory Unit

• Output Device

Answer explanation

In the von Neumann architecture, the Memory Unit is responsible for holding both data and instructions, allowing the CPU to access them as needed for processing.

Which component in the von Neumann architecture is responsible for moving data from the outside world into the computer?

• Output Device

• Control Unit

• Input Device

• Arithmetic/Logic Unit

Answer explanation

The Input Device is responsible for moving data from the outside world into the computer, allowing users to provide information for processing. Other components like the Control Unit and Arithmetic/Logic Unit handle data processing, not input.

Match the following characteristics with their corresponding architecture types.

• von Neumann architecture

• Memory is not addressable

• Harvard architecture

• Data and instructions are stored in separate memory units

• Non-addressable memory architecture

• Only arithmetic operations can be performed

• Arithmetic-only architecture

• The units that process information are separate from the units that store information

Which of the following best describes the function of the Control Unit (CU) in a computer?

• It stores data and instructions

• It performs arithmetic operations

• It acts as the stage unit to ensure all other components act in concert

• It moves results from inside the computer to the outside world

Answer explanation

The Control Unit (CU) coordinates the activities of all components in a computer, ensuring they work together effectively. It does not store data, perform arithmetic, or move results, making the correct choice about its role as a stage unit.

If a computer has 4GB of RAM, how many bytes does it have?

Answer explanation

A computer with 4GB of RAM has 4 gigabytes. Since 1GB = 2^30 bytes, we calculate 4GB as 4 × 2^30 bytes. Therefore, the correct answer is 4 × 2^{30} bytes.

Why are most computers today considered "byte addressable"?

• Each address refers to a word of 16 bits

• Each address refers to a single byte

• Each address refers to a group of four bytes

• Each address refers to a single bit

Answer explanation

Most computers are considered 'byte addressable' because each memory address corresponds to a single byte. This allows for efficient data access and manipulation at the byte level, which is essential for modern computing.

The ALU can perform both arithmetic and logic operations such as (a)  

• addition and subtraction

• AND, OR, and NOT

• storing all data and instructions

• controlling the flow of data betwee

Answer explanation

The ALU (Arithmetic Logic Unit) performs logic operations like AND, OR, and NOT, which are essential for decision-making processes in computing. The other options relate to different functions not performed by the ALU.

What is the purpose of registers in most modern ALUs?

• To store large amounts of data permanently

• To hold a small number of special storage units for temporary data

• To control the input and output devices

• To manage the physical addresses of memory cells

Answer explanation

Registers in modern ALUs are designed to hold a small number of special storage units for temporary data, enabling quick access and manipulation during arithmetic and logic operations.

Which unit in a computer is responsible for interpreting and executing instructions?

• Input Unit

• Output Unit

• Control Unit

• Arithmetic Logic Unit

Answer explanation

The Control Unit is responsible for interpreting and executing instructions in a computer. It directs the operation of the processor and coordinates the activities of all other units.