When designing an information system you first need to consider the output. The output depends on the type of job. If a very basic job is needed you would use a monitor and a printer. The basic input devices are the mouse and the keyboard. Basic output devices are the monitor, the speakers and the printer. I need to consider alternatives so that I can get the best out of my system. The purpose of an input device is to input data or information so it can be converted into the system. Input devices must be fast and accurate. The cost of the product must be reasonably cheap. The main input devices in use today are:
Keyboard Web Camera Joy Stick MICR Mouse Scanner Digital Camera OCR/PMR Barcode Readers Microphone An optical wheel mouse is available to me and a QWERTY keyboard. Keyboard Keyboards are the oldest and most familiar type of input device. The way a keyboard works is that each button that is being pressed closes a switch. This releases a code which the computer converts to the relevant character. The keyboard is called a QWERTY keyboard due to the letters on the top right of it. There are two main faults that could be due to the keyboard. The Transposition Error Around 70% of errors are transposition errors.
This occurs when two letters (or more commonly) numbers are switched with each other. For example, instead of dog a mistake could be dgo or (more commonly) 2345 could be 2435. The Transcription Error This error occurs when the person misreads or mistypes data. This can be caused by reading wrong e. g. 5 = s or 0 = O or the persons bad handwriting. These generally can be corrected due to tools such as grammar checker and spell checker but they don’t detect all errors. Proof reading and double checking will insure that mistakes are corrected. Mouse This is an input device that detects with sensors where it is moving on the desk.
This is converted into digital data which moves a cursor on the screen. There are many types of mice but the two main types are roller ball mouse and an optical mouse. On a roller ball the mouse has a ball that rolls underneath on the desk and sensors pick up the movement. The optical mouse on the other hand takes up to 1500 pictures a second of the beam of red light from the LED. The mouse then moves the cursor depending on the movement of the images of the desk. Output An output device takes data from the computer and displays it in usually recognizable data for the user to read on screen or paper.
There is a range of output devices available for use today, these include: Laser Printers Inkjet Printers Monitor Speakers The output devices that have been available to me are: A 15 inch monitor, a black and white laser printer, an inkjet printer and a colour laser printer. The lasers are very good quality and very fast. Black and white is fine for the payslips. Colour laser printer cartridges are very expensive so with so many employees there is no need for colour. A wider monitor like 17 or even 19 inch monitor would have been useful as I would be able to see more information.