Please enable JavaScript.

Coggle requires JavaScript to display documents.

Network devices ((hubs ((Hubs are hardware devices that can har-e a number…

- - - - Hubs are hardware devices that can har-e a number of de.,'ices or
      - computers connected to them. Ther- are often used to connect together
      - a number of devices to form a IAi\ - for ex.ample, a star network (see
      - later). Its main task is to take any data packet (this is a group of data
      - being transmitted) received at one of its ports and broadcast it to every
      - computer in the network. This essentialh'means that using a hub is not
      - a very secure or efficient method of data distribution.
- - - - Modem means 'modulator demodulator' and is a device that com·erts
      - (i.e. modulates) a computer's digital signal into an analogue signal for
      - transmission over an existing telephone line. It also does the reverse process,
      - in that it converts analogue signals from a telephone line into digital signals
      - (demodulates), to enable the computer to process the data.
      - Modems are essentially used to allow computers to connect to net\vorks (for
      - example, the internet) over long distances using the existing telephone networks.
      - Dial-up modems operate at transmission speeds of about 60 kilobits*
      - per second, which is extremely slow by today's standards.
      - *60 kilobits= 60000 bits. 1 bit refers to a binary digit and has the value 1 or 0.
      - Modern broadband or ADSL (asymmetric digital subscriber line) modems
      - operate at up to 100 Megabits* per second (12.5 Mbytes/second) when using
      - fibre-optic cables ( although the old technology copper cables can usually only
      - offer a maximum of 20 Mbits/second). The term 'asymmetric' actually means
      - that the modem is faster at downloading data (i.e. receiving data) than it is at
      - uploading data (i.e. sending data).
      - 1 byte = 8 bits; 100 megabits = 100 million bits .