CP1610: Introduction to Computer Components The I/O Subsystem: Input Devices

Input Device Topics Purpose of Input Systems Purpose of Common Input Devices

Purpose of Input Devices Input devices are essential in order for users (or other computers and/or devices) to communicate with, and interact with the computer system. They are used to send data to the system bus, and the CPU.

The most common input devices are the keyboard and mouse, however, there are many others. In fact, the keyboard and mouse are so important to the use of modern personal computers that the basic instructions necessary for the computer to interact with them are permanently stored on the motherboard in the system BIOS.

The Keyboard: The keyboard is one of the most important and widely used input devices. Its primary purpose is to allow the user to input text. Some newer keyboards come with additional built-in features, such as volume controls, buttons to power on or off the computer, etc.

The Mouse The mouse is also one of the most important and widely used input devices. It is a pointing device, used to allow the user to move a cursor around the screen in a GUI (Graphical User Interface) system, and to select or manipulate objects on the screen.

Scanners A scanner is a device which ‘reads’ visual data, and transmits that data into the computer system. Visual data can be ‘scanned’ as either text (Optical Character Recognition, or OCR), or as graphics or image files. Scanners can also be used to simulate photocopier and / or fax machines.

Game Controllers Game controllers are similar to mice, in that they serve as pointing devices which allow users to manipulate objects that appear on the screen. Gaming controllers, like mice, also come with a number of built-in buttons that can serve any number of functions, as designated by the software (game) being used.

Joysticks Joysticks are another form of ‘pointing’ input device. They can be used, like mice, to manipulate objects on a screen. They can also be used in other systems (such as aircraft, boats, trains, etc) to input directional data used to guide the movement of vehicles.

Graphics Tablets A graphics tablet is a special pad that allows the user to enter data into the system either by writing it, or drawing it, as if they were using a sheet of paper. Whatever the user writes or draws on the tablet appears on the screen. Graphics tablets are very useful for graphics designers, artists, or engineers working on schematics.

Light Pens A light pen is a computer input device in the form of a light-sensitive wand used in conjunction with the computer's CRT monitor. It allows the user to point to displayed objects, or draw on the screen, in a similar way to a touch screen but with greater positional accuracy. A light pen can work with any CRT-based monitor, but not with LCD screens, projectors or other display devices.

Video Capture Boards: A video capture board is an input device which allows video signals to be input into the computer. A typical application would be for use on computers that run or monitor input from security cameras.

Slide Readers Slide readers are special scanners used to view and capture the images from photographic slides, and convert them into digital images which can be used by the computer.

Film Scanners Film scanners are similar to slide readers, except that they are used to read strips of film, such as those from cameras, and convert their images into digital images which can be used by the computer.

Card Readers Card readers are becoming increasingly popular as input devices. They are used to read the data stored on a variety of memory cards. Another type of card reader is the kind used to read data stored on ID or Security pass cards. These cards are magnetically encoded, and the reader can detect the magnetic field. The particular characteristics of the magnetic field cause the card reader to transmit a binary code to the system (such as a computer), which then can decide to grant or deny access based on its programming.

Point of Sale Systems Point of sale systems are input devices used to gather information from bank cards or credit cards. They collect information such as your account number, so that money can be debited from, or credited to your account. In order for that information to be used by they point of sale device, however, it must be accompanied by a second input – your PIN or passcode.