A-level Computing/AQA/Computer Components, The Stored Program Concept and the Internet/Definitions

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Processor Components: (incomplete)[edit | edit source]

Program control unit - Fetches program instructions from memory, decodes them and executes them one at a time.
Arithmetic and logic unit - The ALU performs arithmetic and logical operations on data such as addition and subtraction; fixed-point and floating-point arithmetic; Boolean logic such as AND, OR, NOT, XOR; and a range of shift operations.
Registers - Fast memory locations inside the processor (or an I/O controller) that may be dedicated or general-purpose.
Internal clock - Derived directly or indirectly from the system clock.
Internal buses - Several internal buses link the control unit, the ALU and the registers.
Logic gates - Used for flow control.


Hardware and Software: (incomplete)[edit | edit source]

Hardware - The physical components of a computer system
Software - programs understood and executed by the hardware that perform tasks
Application software - Used to perform a task that is independent of computer
System software - Software that performs tasks to run computer
General purpose software - type of software that can be used for a variety of tasks
Special purpose software - type of software created to execute one specific task
Bespoke software - type of software designed specifically for an organisation to do the tasks set out by the organisation


Internetː (incomplete)[edit | edit source]

Server - a computer program running to serve the requests of other programs, the "clients”
Client - an application or system that accesses a service made available by a server
Protocol - a set of rules governing the way that devices communicate with each other
Port number - an application or process specific communication endpoint attached to an IP address
URI - A character string identifying a resource on the internet
Internet - a global system of interconnected computer networks that use the standard Internet Protocol suite (TCP/IP)
World Wide Web - a system of interlinked hypertext documents accessed via the internet using the http protocol
Router - a device that interconnects with two or more computer networks, which then interchange packets with each other