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R11 Digital Tech
All topics covered to date
| Term | Definition |
|---|---|
| Hardware | Hardware is the physical components that make up a computer system |
| RAM | RAM is temporary storage of all data and programs that are currently open. |
| ROM | ROM contains the boot-up program which loads the operating system. |
| RAM V ROM | RAM is volatile (forgets everything when power switched off), ROM is non-volatile. RAM is rewritable, ROM is read only |
| CPU | Purpose of CPU is to fetch instructions from memory, decode them and then execute the instructions. |
| Clock Speed | Clock speed is the number of cycles that the CPU can complete in one second (measured in GHz). The faster the clock speed means the CPU can process more instructions per second. |
| Cache Size | Cache Memory acts as a buffer between RAM and CPU. A larger cache size means more data can be held for fast access. |
| Number of Cores | The number of cores is the number of processors (Dual Core = 2 processors, Quad Core = 4 processors). The more cores a CPU has the more information can be processed at the same time. |
| Registers | A component for holding short term memory. Used to store addresses or data currently being worked on |
| Memory Address Register (MAR) | Stores the address of where the next data will be fetched from |
| Memory Data Register (MDR) | Stores the data which has been fetched from RAM |
| Program Counter (PC) | Stores the address of the next instruction. Increases by 1 after each instruction. |
| Accumulator | Stores the data currently being worked on or the arithmetic result of the last calculation |
| Arithmetic Logic Unit (ALU) | Used to perform arithmetic calculations (add, subtract, multiply) and logical operations (>, <, ==) |
| Control Unit | Controls the flow of data within the CPU (Between registers), controls input & output of data to/from CPU and controls timings of signals |
| Virtual Memory | This is when RAM uses a part of the Hard Drive as if it was extra RAM. We use this when RAM is full however it will run slower. |
| Optical Storage | Example: CD, DVD, BluRay Adv: Cheap / Easy to produce lots of copies Dis: Portable but can be scratched |
| Magnetic Storage | Example: Hard Drive (Internal / External), Floppy Disk, Tape Disk Adv: Large storage capacity (Up to 2+ Terabytes) Dis: Not very portable and can be damaged when near magnets |
| Solid State / Flash memory | Example: USB Pen, Solid State Drive (SSD), Memory Card (e.g. SD card), Internal storage Adv: Very portable as there are no moving parts so not damaged if dropped Dis: Most expensive |
| Input Device | An input device allows the user to enter data or instructions into a computer to be processed. |
| Output Device | An output device returns information to the user which is the results of processing. |
| Storage Device | A storage device is required to store files and programs permanently as this is non-volatile. This is also called Secondary Storage. |
| Network | A network is when two or more devices are connected together so they can communicate. These are connected by wires or wireless. |
| Network Advantages | Share peripherals e.g Printers , Internet connection, collaborate on shared documents, Centralised backups (on the server, not each device), Software updates can be pushed out from the server to all devices and Users can log onto any device on the LAN |
| Network Disadvantages | More expensive due to extra hardware and cabling required, Large networks require specialist staff (e.g. a network manager) and Viruses can easily spread between many devices |
| Standalone | A device that is standalone is when it is not connected to a network (and therefore not connected to any other device) |
| Local Area Network (LAN) | A LAN is when devices are connected together in a small area such as a building or site (buildings very close together). The owner of the LAN is responsible for the hardware and maintenance. |
| Wide Area Network (WAN) | A WAN is when LANs are connected together over a large, geographical distance e.g. a town, city or country. WANs rely on the use of cables owned by telecommunication companies (e.g. BT) |
| World Wide Web (WWW) | The world wide web (www) is a collection of websites which are hosted on the internet. Each website is created using HTML (hypertext markup language) with hyperlinks to connect between multiple webpages. |
| Internet | The Internet is a worldwide collection of computer networks that are connected together. It operates on protocols such as TCP/IP. The internet includes other services other than the WWW such as instant message, media streaming and emails. |
| Internet of Things (IoT) | This is when devices are connected to the internet so they can communicate without the need for a user. For example, your fridge could automatically place an order for delivery for products that are running low. |
| Intranet | An intranet is similar to the internet but is a private system. This is when an organisation hosts websites internally (can only access in the work place) which can only be accessed by authorised users. |
| Wi-Fi | Uses radio waves to connect to a WAP. This is a slower connection than cables, and less secure, but is more convenient as devices can move. Subject to interference or affected due to lots of connected devices. |
| Bluetooth | Radio communication and networking protocol. Allows nearby devices to exchange data without a physical connection or additional hardware (e.g. a router). Only small amount of power needed. Can connect automatically. Not affected by other connections. |
| Optical Fibre | Cable of very thin glass strands to send data at a high transmission speed. Transmitted as pulses of light. Each strand is a different data signal. No electrical interference and high bandwidth. Very expensive and requires repeaters over distances. |
| Mobile Communication (4G and 5G) | High speed data access using wireless technology on a global scale. The hardware expensive so the best coverage is in heavily populated areas. The disadvantage for users is these can use a lot of battery life. 5G is more reliable and faster than 4G. |
| Network Interface Card (NIC) | A NIC allows a computer to connect to a network. This allows packets to travel to and from the computer. This either allows a cable to be connected or to connect wirelessly. Each NIC is assigned a unique hardware MAC address which cannot be changed. |
| Network Cables | This is a physical connection between a computer and network hardware. The most common network cable in a LAN is an Ethernet cable. This uses copper. CAT5 being the most common but CAT6 offers better transmission performance. |
| Router | Used to connect two or more devices. Uses a routing table containing the IP addresses of each connected device to send packets to the correct location. These are mainly used to connect two networks together to form a WAN or connect a LAN to the internet. |
| Switch | Used to connect two or more devices together. When packets are sent it creates a direct connection between the sender and receiver so no data collisions. This can handle a large number of connections at once and is ideal for a LAN in a large organisation. |
| Wireless Access Point | Allows devices to connect to a network wirelessly. This includes Wifi & Bluetooth. WAPs provide internet access in public places (Hotspots) |
| Topology | A network topology is the pattern or arrangement in which nodes/devices (i.e. computer, printers, routers etc) are connected together. There are four main topologies: Bus, Ring, Star & Mesh. |
| Bus Topology | All devices are connected to one main cable with terminators at each end. These terminators prevent messages bouncing back along the main cable. |
| Bus Advantages | Easy to setup and Cheap to install |
| Bus Disadvantages | Data collisions as data travels in two directions. This leads to slow data transfer and If main cable breaks then network fails |
| Ring Topology | All devices are connected together in a ring shape with all data being sent in one direction until the destination is reached |
| Ring Advantages | No data collisions as data moves in one direction and Easy to add new devices |
| Ring Disadvantages | If one devices breaks then network fails and Not secure as all data can be ‘seen’ by other devices |
| Star Topology | All devices have a direct, non-shared, connection to a switch/hub in the centre. Most common. |
| Star Advantages | Very reliable as if a device breaks the network is unaffected and Most secure as no shared cables |
| Star Disadvantages | Expensive due to extra cables and hardware required and If hub breaks, the network fails |
| Servers | A server is a high-powered computer that provides data and services to other computers. A server manages several services including web access, printing, email, security, backups, updates and file storage. Can be split into individual servers. |
| Web Server | Web servers are responsible for managing all internet access (websites) and can also host websites so they can be accessed across the internet. |
| File Server | On file servers, all data on the network must pass through it. File servers store data and software for users to use from any workstation. |
| Mail & Print Server | Mail & print servers manage incoming & outgoing emails and users printing to share printers. |
Created by:
ssmith897
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