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Most general purpose computers are based on von Neumann architecture. This includes using the fetch-decode-execute cycle to process program instructions. Computer performance depends on cache size, clock speed and the number of cores.

Primary storage is a key component of a computer system that enables it to function. Primary storage includes random access memory (RAM), read only memory (ROM), cache and flash memory. Each of these have different uses within the computer.

Computers need to be able to store programs and data indefinitely when the power is switched off. Magnetic, optical and solid state devices are different types of secondary storage used to store the data and programs. Each type has different functions in terms of suitability, durability, portability and speed.

Devices can be networked using different hardware, such as routers, hubs, switches, gateways and bridges. They can cover local areas (LANs) or wider areas (WANs). Networks are constructed using different topologies, including ring, bus, star and mesh. All of these differences have advantages and disadvantages to users.

Networks operate on the principles of communication and sharing. Unfortunately, these principles mean that network traffic and data can be more easily accessed by people who have no authority to do so. Different vulnerabilities need to be identified and measures put in place to protect systems from them.

Binary data can represent numbers, graphics, sound and characters. It is then organised and manipulated differently. Data can also be stored in arrays, records or external files and go through validation or verification checks to ensure accuracy.

Arrays form the basis for how data is stored within a program. They must be declared with meaningful identifier names and appropriate data types that match the data. Without the correct data structures and data types, programs will not work.

Operating systems control a computer’s resources and provide an interface for users to be able to communicate with these resources. Utility software helps to maintain the system.

Programming languages can be categorised as high-level and low-level. They each have very different characteristics and are used for different purposes. Machine code and assembly languages are very different to the languages most programmers use.

Algorithms are step-by-step plans for solving problems. They are a starting point when writing a program. Algorithms can be designed using pseudo-code and flowcharts.

Sorting and searching are two of the most frequently needed tasks in program design. Common algorithms have evolved to take account of this need, such as linear search, binary search, bubble sort and merge sort.

Translators like compilers, interpreters and assemblers are needed to translate programs written in high-level languages into the machine code that a computer understands. There are different stages in the compilation process. Tools exist to help programmers develop error-free code.

The use of computers has brought about environmental, ethical and legal issues and concerns. These increasingly affect people's daily lives.