Computer Architecture – von Neumann and CPU Operations

What is the primary role of the CPU in a computer?

• To manage the computer's power supply.
• To store data permanently in the hard drive.
• The primary role of the CPU is to execute instructions and process data.
• To provide internet connectivity to the computer.

Answer explanation

The CPU is responsible for executing the instructions given by the software, which includes arithmetic, logic, control, and input/output operations.

The _______ _______ (PC) holds the address of the next instruction to be executed by the processor.

Answer explanation

The Program Counter holds the memory address of the next instruction so that the CPU knows where to fetch the next operation.

Describe the difference between the Memory Address Register (MAR) and the Memory Data Register (MDR).

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Answer explanation

The MAR holds the address from which data is to be fetched or written, while the MDR holds the actual data being transferred between the CPU and memory.

Categorise the following as either an input device, output device, or both:

Groups:

(a) Input

,

(b) Output

,

(c) Both

• Webcam
• Keyboard

• Touchscreen

• Mouse
• Monitor
• Speakers
• Headphones
• Projector
• Microphone
• Printer

Answer explanation

A keyboard only inputs data, a monitor only outputs data, while a touchscreen allows both input and output.

Match the bus types with their correct description:

• Address Bus

• Transmits data between CPU and memory

• Control Bus

• Sends control signals like read/write

• Data Bus

• Carries the address of the data

Answer explanation

Each bus in the computer architecture has a specific function: the address bus carries memory addresses, the data bus carries actual data, and the control bus sends signals for operations.

If a processor operates at 4 GHz, how many instructions can it execute per second?

Mathematical Equivalence

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Answer explanation

A 4 GHz processor means it can process 4 billion cycles per second, translating into 4 billion instructions per second.

Reorder the stages of the FDE Cycle into reverse order.

• Execute instruction

• Decode instruction

• Fetch instruction

Answer explanation

This is the standard sequence of operations the CPU performs to execute a program. I have asked for the reverse order to make sure you were reading the question carefully. This will provide invaluable throughout the course.

On the diagram of von Neumann architecture, click on the memory unit.

Answer explanation

The memory unit in von Neumann architecture stores both the data and the instructions, which are accessed by the CPU for processing.

The ​ (a)   handles arithmetic and logic operations, the ​ (b)   manages instruction execution, and ​ (c)   hold temporary data.

• ALU (Arithmetic and Logic Unit)
• CU (Control Unit)
• registers
• CPU (Central Processing Unit)
• RAM (Random Access Memory)
• Motherboard
• GPU (Graphics Processing Unit)
• cache
• ROM (Read-Only Memory),
• hard drive

Give a brief explanation of how the Control Unit (CU) interacts with the Arithmetic Logic Unit (ALU) and memory during program execution.

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Answer explanation

The Control Unit reads instructions from memory, decodes them, and sends signals to the ALU and other components to perform the necessary operations.