Computer Science

CPU

a chip in the computer which decodes then executes program instructions

register

small area of memory within the CPU where data is stored temporarily to avoid the delay in copying to and from main memory

Von Neumann Architecture

several registers along with the fetch-execute cycle and how the CPU interacts with main memory

Memory Address Register

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

Memory Data Register

contains the instruction which has just been copied from main memory

Program Counter

contains the address of the next instruction to be fetched from memory

Accumulator

stores the result of the last operation

Embedded Systems

specialist hardware and software built into a device with a single specific purpose

Primary Storage

holds the data, programs and instructions currently in use

RAM

stores programs and data before they are processed by the CPU

ROM

data can be retrieved but not changed, used to store programs for embedded system

volatile

lost when the computer is turned off

non volatile

data is not lost when the computer is turned off

virtual memory

space on the computer’s hard drive used as main memory (RAM), slower than main memory

optical storage

secondary storage which stores data on a spinning plastic or metal disk, data is read from and written do the disk using a laser

magnetic storage

secondary storage which uses magnetic fields to store data

solid state storage

secondary storage which uses flash memory to store data, no moving parts and are much faster than optical or magnetic storage

hard disk

magnetic storage which can store large amounts of data, number of internal disks and a read/write head

DVD (Digital Versatile Disk)

high capacity optical storage disk commonly used for video storage

CD (Compact Disk)

optical storage disk often used to store music, around 800mb

SSD (Solid State Drive)

solid state storage drive which carries out the function of a traditional HDD, more expensive and lower capacity

why are SSDs much faster and less easy to damage than HDDs

no moving parts

metadata

additional data about a file such as when it was created

analogue

continuously varying signal, usually presented as a curved line, such as sound or temperature

Network

2 or more computers connected together for the purposes of sharing data or resources 

Client-Server networks

where resources of processing are carried out by a central computer with other devices, accessing resources via the network

Peer to Peer

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 2 or more different networks together

switch

provides computers and other devices with a wired connection to a network