Fundamentals of computer organisation and architecture

The fundamentals of computer organisation and architecture form the backbone of understanding how a computer system operates at the hardware level. This topic covers the internal structure of a computer, including the central processing unit (CPU), memory hierarchy, and input/output mechanisms. You will explore how data is represented, stored, and processed, and how the fetch-execute cycle drives program execution. Understanding these concepts is crucial for appreciating how software interacts with hardware and for optimising performance.

In the AQA A-Level Computer Science specification, this topic is essential for building a foundation in systems architecture. It links directly to topics such as assembly language, operating systems, and performance analysis. By mastering this area, you will be able to explain how factors like clock speed, cache size, and core count affect processing speed, and how different architectures (e.g., von Neumann vs. Harvard) influence system design. This knowledge is not only exam-relevant but also vital for careers in hardware engineering, embedded systems, and low-level programming.

This topic also introduces key concepts like the stored program concept, where both instructions and data are held in memory, and the role of buses in data transfer. You will learn about the control unit, arithmetic logic unit (ALU), and registers such as the program counter (PC), memory address register (MAR), and memory data register (MDR). These components work together to execute instructions, and understanding their interplay is critical for answering exam questions on CPU performance and pipelining.