Input Devices

Input Methods

Computers (along with other information-handling systems) process data to produce some form of useful output. To do this, a computer needs some data to be fed into it - this is the INPUT. There are a number of different ways in which a computer can accept this input. Most methods, though, fall into two main areas: manual input methods (entering data by hand); and automatic input (such as data logging).

1 Manual Input Methods

The main manual input method for many people is the QWERTY keyboard - the one shown here has 105 keys which allow the user to enter both upper and lowercase text, numbers and some special characters (such as £ $ % ^ &).
The keyboard is a direct decendent of the keys on a typewriter. The typewriter was invented in 1872 and was once a very common machine for producing formal text. The keys on a QWERTY keyboard were originally arranged so that common letter pairs (such as 'TH' and 'UN') weren't together. This meant that the mechanism that printed the letters was less likely to jam.
People got so used to using this keyboard layout that it continued to be used in the modern computer (or word-processor) keyboard.

As graphical user interfaces (like Microsoft Windows and Mac's OS X) became more popular people needed a way to point to different menus and icons on the computer screen. Although you could use the cursor keys on a keyboard it was much easier to use a mouse.
The mouse was originally used by designers who wanted to draw simple shapes on the computer screen, for example, during Computer Aided Design (CAD) applications.

Nowadays, designers and artists use a graphics tablet to work on the computer. A graphics tablet is made up of two main parts: a pen (or stylus) and the tablet itself. If you draw on the tablet with the special pen then your drawings can be converted to lines and shapes on the computer screen.
It is much easier to draw lines and shapes with a pen (as we have all used pens since we were little) so many people prefer them to using a mouse.
Modern paint programs allow the artist to change their pen strokes into pencil lines, brush strokes, airbrush sweeps and other effects. In this way an artist can use a variety of tools while holding the same pen!

Another way to get graphic images into a computer is to use a scanner or digital camera. Some artists prefer to use this method as it enables them to work using their brushes and pens on paper or canvas before scanning the images into the computer to complete using specialised software (such as Adobe's Photoshop).

The concept keyboard is a touch sensitive board that can be connected to a computer. The useful thing about the concept keyboard is that different sheets (or overlays) can be placed on top of it and the person using the keyboard can use their fingers to press the pictures on the sheet.

The keyboard in this picture has been used with children who are learning to read and write. The child can press the pictures on the keyboard and the word for that picture appears in a word processor on the computer.
Similar keyboards are also used at shop tills (such as fast-food outlets) because pictures of the food on offer can be placed on the keyboard. The keyboards are easy to keep clean and can be changed if a new product becomes available.

Answer these questions:

  1. What input device would you use to get picture of a painting into the computer ?
  2. What device must you have to use Windows or OS X ?
  3. Apart from a scanner, what other device would a computer artist use ?
  4. What would you use to enter text into a computer ?
  5. What type of device has overlays with different pictures on them ?


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2 Direct (automatic) Input Methods

There are some situations when it would be impossible (or very impractical) to enter data by hand. The National Lottery scheme uses Optical Mark Readers (OMRs) to convert the marks that you make on a lottery ticket (shown here). This is because the OMR machine is much more accurate than someone with a keyboard would be.

It may seem easy to enter six numbers (all under 50) without making a mistake. But, if you have to do this hundreds of times a day, for a queue of grumpy customers then you may well make a mistake. If that mistake meant that your customer did not win the jackpot then they may get a little grumpier!

On the other hand, if you want to measure certain conditions for very long or very short periods of time then you need a data-logging device.
Although you could stand outside for a week measuring the air temperature with a thermometer (and writing the results in a notebook) it is far easier - and more accurate - to set up a data-logger to record the temperature for you. The data-logger will not get bored, miss a reading, or need to stop for food or the toilet.

Why not go to the data-logging page and look at some examples of data-logged data ?

Both the data-logger and the OMR machine are devices for collecting large amounts of data accurately and entering them directly into the computer.

Answer these questions:

  1. What does OMR stand for ?
  2. Why are OMR tickets better than keyboards for getting your lottery numbers ?
  3. What device could you use to automatically collect temperatures ?
  4. What form of input device is a keyboard ?
  5. What form of input device is a data-logger ?

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