Key definitions - Paper 1 Flashcards
CPU (Central
Processing Unit)
A chip within the computer which controls the operation of all parts of the
computer and decodes then executes program instructions.
Cache
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.
MAR
It contains the address of the instruction currently being read
from or written to main memory.
MDR
It contains the instruction which has just been copied from
main memory.
Program Counter
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.
Accumulator
Stores the result of the last operation
CIR
Holds the instruction that is currently being decoded and executed
Cores
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.
Embedded
System
Specialist hardware and software build into a device with a single specific
purpose. They are usually found within appliances such as washing
machines.
Primary Storage
Also known as memory. Holds the data, programs and instructions currently in use.
Virtual Memory
Space on the computer’s hard drive used as main memory (RAM). Virtual
memory is slower than main memory.
Optical Storage
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.
Magnetic
Storage
A type of secondary storage which uses magnetic fields to store data. A
read/write head reads and writes data from the media.
Solid State
Storage
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.
Character Set
A system for representing characters in binary, each character is
assigned a unique binary number.
Metadata
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.
Colour Depth
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.
Sample Rate
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.
Bit Depth
The number of bits available for each sample. The higher the bit depth,
the more bits available and therefore the better the quality.
Lossy
Compression
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.
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.
Client - Server
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.
Peer to Peer
A network setup where all computers have an equal status and function
as both client and server.
Network Hardware:
Wireless Access Point
Router
Switch
NIC (Network
Interface Card)
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
DNS (Domain
Name System)
A system which links a URL or other human readable name with an IP
address.
The Cloud
A term for accessing storage or other resources remotely across The
Internet.