In this section we are going to look at different input devices and input media and justify why items selected are suitable to solve problems.
In this chapter we are looking at:
• The broad characteristics of a sample of current input methods.
• Appropriate situations where each could be found.
• Input devices and media used for each method of input.
• Any limitations of a sample of current input devices and media.
The concept of ICT is input of data, processing of the data to transform it into information and then the output of the information.
There are two types of input devices, manual entry and automatic entry.
If the volume of data is large then
automatic data entry is far more efficient than manual, despite the cost of installation.
Training and maintenance
are major factors when deciding on the most suitable type of input device. You should be thinking about the kind of input devices that the client uses and not the kind of devices that your school or college uses.
Thinking about the practical work that you will be producing for this unit there are four types of data that can be entered into a computer system: text, images, moving images and sound.
Devices used to enter text
The most appropriate way of entering text manually is to use a keyboard; automatically the most appropriate way is to use a scanner and Optical Character Recognition software. There are many types of keyboard, the most popular one is the QWERTY keyboard although there are ergonomic keyboards and even ones with icons (these are concept keyboards), which can be found in public houses or fast food restaurants. Text can be easily entered into the computer system and a user does not need to be an expert typist to enter the data into the system. The main limitation is the size of the device; if it is too small then it is difficult to type and if it is too large then it becomes cumbersome.
A Sinclair ZX81 computer had a keyboard that was about half the size of a standard keyboard and
when one key was pressed there was a chance of hitting four other keys.
If there is a great deal of text to be entered into the computer system then automatic text entry would be far more efficient. This could be achieved by the use of a scanner and then changing the scanned image into text using optical character recognition software. A scanner reads a paper document and changes the data into a graphic, then OCR software takes this graphic and using templates of characters selects a character that closely matches the one on the image. There are problems with some characters, for example rn could be read as an m. The cleanliness of the input document and the resolution of the scanner will affect the result. A
modern example of the use of OCR technology is ANPR (Automatic Number Plate Recognition). This uses a camera in the same way as the scanner to record a number plate, and then can identify the car using templates, and the details of the registered owner, etc. using the DVLA database.
Pointing devices
Sometimes input devices are not used to enter data like sounds or text; they are used to point at icons, for
example, and click on these. Most computers have mice or other pointing devices like keyboard pads. Essentially they are point and click devices. The main problems with these devices are that traditional mice can become clogged with dirt and grease and this impairs their operation; also mice need a large surface on which to work.
The problem with the keyboard pad is that the device is so small that any movement is accentuated across the
screen.
Touch screens
These are used in public places like train stations or public libraries. These are sensitive screens that work in the same way as a mouse; as you touch the screen your finger acts as a pointing device. The images on the screen need to be large as it is difficult to point to a small area.
Devices used to enter images
Sometimes the user will wish to enter an image, as they draw it; they would use a graphics tablet to do this. The tablet uses a stylus which draws on the flat bed on the tablet. This allows for drawings to be produced from scratch or to be traced from an original. Part of the tablet could be an area where the thickness of lines, colour, fill, etc. can be selected.
Mark sensing
Every day in the UK a mark sensing system is used to record someone’s lottery numbers. The pink cards that are used have specified boxes where the customer colours in the lozenge (that’s the technical word for it), and then this is fed into the lottery machine. The reader notes the position of the mark and from that can store the day, the number of plays, and then numbers. Multiple choice examination papers use the same kind of operation when they are read. The advantages of this type of system is that large amounts of data can be rapidly read; however if the mark is not clear enough or there is a smudge on the paper then the data can be easily misread.
Magnetic Ink Character Recognition.
This is a dying method of data collection, as it tends to be used on cheques only.
This is by far the most secure way of reading data but by far the most expensive.
The data is written on the bottom of the cheque in magnetic ink; it is then magnetised as it is read. This means that even if the cheque is photocopied it cannot be read by the computer; therefore the cheque is safe. Cheques, however, are becoming less and less popular; if in the near future they vanish, so will MICR.
Bar code Reading
Bar codes are appearing on more and more items nowadays. In the past they tended only to be on food goods bought in the supermarket but nowadays you find them on magazines, library cards, parcels, etc. They are cheap and easy to use, hence their popularity. They are read either by scanner or by hand-held wand.
The disadvantage of using bar codes is that if they crease then there may be problems with reading them.
Magnetic Stripe, Chip and PIN and Smart cards Magnetic stripes are used on cards like bank cards although most bank cards now use chip and PIN. The magnetic stripe on the back of the card holds data and is read by a magnetic card reader. This is very fast and accurate, although a strong magnetic field could destroy the data. They are used on train and tube tickets as well as parking tickets.
A chip and PIN card has a microprocessor on the card which holds similar data to the magnetic stripe. The card is authenticated by the use of a Personalised Identification Number. A special reader is used to read the card. Cards like the London Oyster card also use a microprocessor which uses a special card reader. The chip holds the amount of money that has been placed on the card; this then makes it a smart card. As the card is read an amount of money is removed from the chip.
Touchtone phones and speech recognition
Other ways of entering data into a computer is through the use of sound. A touch tone phone, one with buttons, allows the user to select items from a menu using the numbers of the phone’s key pad. Each key emits a note and it is this note that the computer senses in order to make the choice. In more modern systems the touch tone is replaced by speech. So the user would either press a key or speak the number. These are used in BT’s 1571 answering phone system or Virgin Rail’s online booking system where the user tells the computer the details.
Speech recognition systems are fast and efficient although if there is a great deal of background noise then the
command can be distorted.
Digital cameras and camera phones
With the improvement of technology digital cameras and camera phones are getting better and better. Having
taken the photographs with either of these devices we then need to upload them into the computer. This is
achieved by using a cable and then sending the pictures into the computer where they can be stored and used.
Digital cameras are not input devices on their own they need to be attached to a computer using a USB port.
