1. OCR GCSE (9-1) Computer Science (J276)
(01) Computer Systems L2

2. Last lesson, we looked at:
1.1 Systems Architecture
Recap….
Last lesson, we looked at:
what is a computer system;
defining a computer system;
understanding the architecture of a computer system.

3. Recap…. 1.1 Systems Architecture Define a computer system.
A Computer System is a combination of hardware and software components that allow input, processing and output of data.

4. 1.1 Systems Architecture Computers systems are all around us. They
are not just the PCs on the desk but include
mobile phones, cash machines

5. 1.1 Systems Architecture
All computer systems must have input devices that get data from the real-world. This could be a mouse and keyboard on a conventional PC but could be a temperature sensor (thermistor) in a commercial greenhouse or the microphone on a mobile phone. Input
devices take real-world data and convert it into a form that can be stored on the computer.

6. 1.1 Systems Architecture
The input from these devices is processed and the computer system will generate outputs. The output device could be a conventional computer screen or it could be a motor that opens a greenhouse window or the speaker that produces sound on a phone.

7. 1.1 Systems Architecture Learning Objective:
Understand the purpose of the CPU;
Describe the structure of the CPU;
Describe the common components and their function: ALU, CU and Cache.
We are going to spend the next 3 lessons looking at the Fundamentals of Computer Systems.

8. Keywords: Central Processing Unit (CPU) Von Neumann Architecture
1.1.1 Understand the purpose of the CPU; Describe the structure of the CPU; Describe the common components and their function: ALU, CU and Cache.
Keywords:
Central Processing Unit (CPU)
Von Neumann Architecture
MAR (Memory Address Register)
MDR (Memory Data Register)
ALU (Arithmetic Logic Unit)
Accumulator

9. 1. 1. 1 Understand the purpose of the CPU; 1. 1
1.1.1 Understand the purpose of the CPU; Describe the structure of the CPU; Describe the common components and their function: ALU, CU and Cache.
Recap….
Define a CPU.
It is the part of the computer that controls the interpretation and execution of instruction i.e. it processes the raw data and turns it into information.

10. The “brains” of the computer
1.1.1 Understand the purpose of the CPU; Describe the structure of the CPU; Describe the common components and their function: ALU, CU and Cache.
The central processing unit (CPU) of a computer is the hardware that executes programs and manages the rest of the hardware.
The “brains” of the computer
Carries out instructions (Executes Instructions)
Processes Data
Retrieves Data/Instructions from Main Memory (Fetch)
Stores Data into Main Memory once Executed

11. Complete the Systems Architecture CPU worksheet
1.1.1 Understand the purpose of the CPU; Describe the structure of the CPU; Describe the common components and their function: ALU, CU and Cache.
TASK 1
Complete the Systems Architecture CPU worksheet

12. What is the purpose of the processor?
1.1.1 Understand the purpose of the CPU; Describe the structure of the CPU; Describe the common components and their function: ALU, CU and Cache.
TASK 2
What is the purpose of the processor?
Where are instructions that are currently in use stored?
What else is stored in main memory?
How are instructions executed by the processor?