GCSE Computer Science OCR

Computer Systems

Basics of Computer Systems

• A computer system includes hardware, software, and data which all work together.
• Hardware includes the physical components of a computer, like the CPU, memory, and input/output devices.
• Software is the set of instructions that direct the hardware to carry out tasks.
• Operating systems are a vital type of system software that controls overall operation of a computer.

Characteristics of Contemporary Processes, Software and Hardware

• A process in computing is an instance of a program in execution. It needs resources like CPU time, memory, and files, and it can be made up of multiple threads.
• Multithreading allows a computer to perform many different tasks at the same time.
• Contemporary systems can also implement parallel processing, where many processors perform operations at the same time.
• The speed of a processor is measured in gigahertz (GHz), while its power is measured in terms of the number of cores it has.

Systems Architecture

• The CPU, or central processing unit, is considered the brain of the computer. It executes program instructions. The speed at which the CPU processes data is called clock speed.
• Volatile memory, like RAM, requires power to keep the stored information accessible. Once the power is gone, the data is too.
• Non-volatile memory, like a hard drive or flash memory, stores information even when not powered.
• The motherboard is the main circuit board in a computer, housing the CPU, memory, and input/output device connections.

Software and Software Development

• System software, like the operating system, coordinates and controls hardware functions.
• Application software enables users to complete tasks, like word processing or web browsing.
• A compiler translates the entire code of a program into machine code in one go, whereas an interpreter translates the code line by line, executing each line as it goes.
• Low level programming languages, like assembler, are closer to machine code and specific to individual computer architectures.
• High level programming languages, like Python or Java, are closer to human language and are easier to write, read, and maintain.

Exchanging Data

• Networks are systems of interconnected computers that can send and share data.
• LANS, or Local Area Networks, connect computers in a small geographical area, like a school.
• WANS, or Wide Area Networks, cover a large geographical area, often made up of interconnected LANS.
• Protocols are sets of rules that dictate how data should be transmitted across networks.
• HTTP, or Hyper Text Transfer Protocol, is the protocol for transferring multimedia web pages.

Data Types, Data Structures and Algorithms

• Computers use different data types like integer, character, or Boolean values.
• A data structure is a specialized format for organizing and storing data, like arrays, stacks, and queues.
• An algorithm is a set of instructions for solving a particular problem. It can be represented with pseudocode or a flowchart.

Legal, Moral, Cultural and Ethical Issues

• Understanding the legal, moral, cultural, and ethical issues in computing is crucial. This includes topics like data protection, integrity, accessibility, and intellectual property.