Key definitions - Paper 1

A chip within the computer which controls the operation of all parts of the computer and decodes then executes program instructions.

High speed memory built into the CPU. Frequently used Instructions are copied to cache memory allowing them to be accessed more quickly and therefore increasing the speed of the CPU.

It contains the address of the instruction currently being read from or written to main memory.

It contains the instruction which has just been copied from main memory.

It contains the address of the next instruction to be fetched from memory. It is updated each time a new instruction is fetched to contain the address of the next needed instruction.

Stores the result of the last operation

Holds the instruction that is currently being decoded and executed

Some CPUs have more than one core, each containing its own ALU and registers and therefore capable of carrying out instructions independently. The more cores, the more instructions the CPU can process at once and therefore the faster it performs.

Specialist hardware and software build into a device with a single specific purpose. They are usually found within appliances such as washing machines.

Also known as memory. Holds the data, programs and instructions currently in use.

Space on the computer’s hard drive used as main memory (RAM). Virtual memory is slower than main memory.

A type of secondary storage which stores data on a spinning plastic or metal disk. Data is read from and written to the disk using a laser.

A type of secondary storage which uses magnetic fields to store data. A read/write head reads and writes data from the media.

A type of secondary storage which uses flash memory to store data. They have no moving parts and are much faster than optical or magnetic storage.

A system for representing characters in binary, each character is assigned a unique binary number.

Additional data about a file such as when it was created or who created it. Commonly used with photos to store things like the make of camera or location the photo was taken.

The amount of bits available for colours in an image. The higher the colour depth the more colours available and therefore the more realistic the image will appear.

The number of samples taken in one second. This is measured in hertz (Hz), 1Hz is one sample per second. The higher the sample rate, the more samples per second and therefore the higher the quality of the file.

The number of bits available for each sample. The higher the bit depth, the more bits available and therefore the better the quality.

A compression method which reduces the file size by removing certain data. The original file cannot be restored from the compressed version but the file is reduced by more than with lossless compression.

A compression method which reduces the file size without losing any data. The original file can be restored from the compressed version, but the file size is not reduced by as much.

A network setup where resources or processing are carried out by a central computer (called a server) with other devices (called clients) accessing resources via the network.

A network setup where all computers have an equal status and function as both client and server.

Wireless Access Point Uses a wireless radio to allow devices to connect wirelessly to an existing network. Router A device which connects two or more different networks together allowing them to communicate with one another. Switch A device which provides computers and other devices with a wired connection to a network. NIC (Network Interface Card) A component within a computer or other device which allow it to connect to a network. The card provides the physical connection to the network