A-level Computing/AQA/Print version/Unit 2/Definitions
- Boolean variable: has two discrete values: true or false
- Truth Table: a table that shows the results of applying a logical operation
- Boolean equation: an equation that expresses a boolean output in terms of boolean inputs and the functions applied
- Logic gate: an electronic circuit that performs a boolean function
- Hardware: Electronic circuits that a computer is assembled from/ The platform on which software executes
- Main memory: Memory that is directly accessible to the processor
- Memory location: a separately addressable area of main memory
- RAM: random access memory; volatile memory in which the locations can be accessed directly in any order
- ROM: read only memory; non-volatile memory that cannot be written to after it has been set up
- EEPROM: electrically erasable programmable read only memory; read only memory which's contents may be altered
- Computer Bus: a set of parallel wires connecting independent components of a computer
- System Bus: the main set of buses connecting the processor, main memory and I/O controllers, consisting of the data, control and address bus
- Peripheral: a computer device that is not part of the central processing unit
- I/O device: a hardware unit that sends or receives data or stores data, by communicating with the processor via a I/O controller
- I/O controller: an electronic circuit that connects to a system bus and an I/O device
- Secondary storage: permanent data storage not directly connected to the processor
- Memory address: a unique numeric code corresponding to a location in memory
- Stored program concept: a program must be present in main memory to be executed; it is processed by fetching machine code instructions in sequence from the main memory and executing these codes, one at a time in the processor
- Register: a very fast memory location inside the processor or I/O controller
- General purpose registers: a register that is not assigned a specific role
- Dedicated registers: a register assigned a specific role by the processor designer, e.g. the MBR or MAR
- Clock speed: the frequency in megahertz at which the processor executes instructions
- Word length: the number of digits in a binary word, e.g. 8-bits
- Bus width: the number of wires in a bus
- Machine code instruction: a binary code that a machine can understand
- Compiled high level language program: a program translated into machine code before it is executed on a computer
- Op-code: the part of a machine code instruction that denotes the basic machine operation, e.g. ADD
- Operand: the part of a machine code instruction that represents a single item of data used by the op-code
- Instruction set: the set of bit patterns or binary codes for the machine operations that a processor has been designed to perform
- Track: one of the concentric rings on a platter of a hard disk
- Sector: a subdivision of a track
- Disk block: the smallest unit of transfer between a computer and a disk; the size of a sector (size as in binary length)
- USB: Universal Serial Bus; allows peripherals to be connected using a standard interface socket
- Access time: the time the time between accesses on a storage device
- Software: a series of instructions that are executed by the hardware
- Assembler: translates assembly code into machine code
- Compiler: translates high level language code into object code
- Interpreter: analyses and executes high level language code line by line
- Bespoke software: written for a customer's specific need
- General purpose software: software that can be used for many different tasks
- Special-purpose software: software designed to support a specific task
- Internet: a network of computer networks and computers using unique IP addresses and communicate via the TCP/IP protocols
- Gateway: connects networks that use different link layer protocols
- Router: connects networks that use the same link layer protocol
- IP-Address: a unique address that identifies a computer or other device on a network
- WWW: World wide web; a system of interlinked hypertext documents accessed via the internet
- Domain name: a name that identifies one or more IP addresses
- FQDN: Fully Qualified Domain Name; it consists of a host ID and domain name
- DNS server: server that translates fully qualified domain names into IP addresses
- URL: Uniform Resource Locator; a URI that identifies a resource by its network location
- URI: Uniform Resource identifier; specifies how to access a resource on the internet
- Server: a software process that provides a service requested by a client
- Client: a software process that requests and uses the services provided by a server
- Client-Server model: a client software process initiates a request for a server software process to respond to
Category:Book:A-level Computing#AQA/Print%20version/Unit%202/Definitions%20