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  • Level: GCSE
  • Subject: ICT
  • Word count: 1829

Introductory Communications and Input Output Devices

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Modem and Digital & Analogue Data Ordinary telephone lines can transmit sound signals because they are designed for speech. These signals are in analogue form. To transmit digital data into analogue data, it must be converted so when the analogue data reaches the end of the telephone line it must be converted back to digital format for a computer to accept it. A device called a MODEM (Modulator Demodulator) does this. Differences Analogue and digital data is very different. Digital lines are a lot more expensive to install and use compared to normal telephone lines. Modems must be purchased for use with normal telephone lines. Digital lines have a much higher bandwidth so the transmission rate for information is much quicker. Advantages & Disadvantages There are many advantages of using common networks, such as the internet, but there are also disadvantages. Local networks can mean that software and data can be shared, and all the users can communicate with one another. However, the installation software can be quite high and there is an extra task making sure that shared resources are safe and secure. The network can fail and cause chaos, or it could operate slowly if a lot of users are logged on. User IDs and Passwords When using a networked computer, it is important that we can only access data that is ours or that is shared. ...read more.


Mouse balls need to be cleaned regularly to make the mouse function properly. Joystick Scanner Moves a pointer on the screen. This is often used in computer games. There is an easy feel of direction due to the movement of the stick. More arm and wrist movement is required to use the joystick and so some people find it difficult. Joysticks are not robust enough and do break easily when playing games. Digital Camera Input Taking photographs to be put on the computer to be edited printed used in documents and presentation and to be posted on the internet. No film is required so therefore there are no developing costs. You can edit the image the way you want it (e.g. bigger, smaller etc). Digital cameras are a lot more expensive than normal ones. When they are full they most be loaded to a computer or deleted before the camera can be used again. Scanner Input This is another way of inputting still images. A scanner can be used to publish magazines and newspapers. Any image can be transferred from paper to a document, and then may be stored in documents and can be posted on the Internet. Images can take up a lot of memory space. Device Input/Output Uses Advantages Disadvantages Remote Control Input Can be used to input data from a distance. ...read more.


Dot-Matrix Printers Output These are ideal when carbon copies are needed. This is because they are impact printers, so the head bangs onto the top of the paper; the carbon paper transfers a copy to the paper beneath the carbon paper. They are often used for invoices and delivery notes. They produce carbon copies unlike laser and ink-jet printers. It is very cheap and reliable. The running costs are low as are the printouts. These are very noisy, slow and they produce very poor quality output. Plotter Output Often used for building plans, graphs and 3-D drawings. Also, they are used for engineers who are building bridges, machines, etc. Drawings are of the same quality as experts. Larger paper sizes can be used. Plotters are slow as they draw each line separately. Drawings are high quality but it is not suitable for text. They re a lot more expensive than printers. Normal plotters have a limit to the amount of detail they ca produce, but there are high-density drawings for things like a circuit board. Speakers Output A program that produces sound needs a headphone or speakers to be heard. For example a program that teaches a foreign language needs a speaker to playback. Everyone around can hear the sound from the speaker, so it is useful for a presentation that needs to be heard. The output can disturb others. High quality external speakers are expensive. Device Input/Output Uses Advantages Disadvantages Control Devices (lights, buzzers, robotic arms, motors) Input ?? ?? ?? ?? Introductory Communications ...read more.

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