OCRJ277 CompSci 1.1 – Systems architecture L1

The first of 3 complete lessons on OCR J277 Content of Computer Systems 1.1 – Systems architecture - 1.1.1 Architecture of the CPU.

Each lesson will have a:

• PowerPoint Presentation
• A Worksheet with Activities (With Answers)
• A Questions sheet (With Answers)
• A Multiple Choice Quiz (With Answers)

In this lesson, this is what will be covered.

The Central Processing Unit (CPU) is often called the “brain” of the computer, as it performs the essential task of processing instructions that allow software to function. Its primary purpose is to execute instructions, carrying out commands from programs to produce outputs based on given inputs. This process is known as the fetch-execute cycle.

The fetch-execute cycle involves three main stages:

1. Fetch: The CPU retrieves an instruction from memory, identified by the program counter, which keeps track of the address of the next instruction to be executed.

2. Decode: The fetched instruction is interpreted, determining what action the CPU needs to perform. This could involve arithmetic, moving data, or interacting with hardware.

3. Execute: The CPU carries out the instruction, completing tasks such as calculations, data transfers, or even accessing other parts of memory to continue processing.

After executing, the cycle repeats, allowing the CPU to perform millions or billions of instructions per second, which is essential for the smooth operation of any computer system.

All resources can be adjusted as needed for the learner.