Hardware is the physical devices that can be touched and used to send or receive messages or information to and from one person to another person. The components of a computer system are: Input devices- these get data into the computer. The main processor unit- this manipulates the data. The storage devices- these save data. The output devices- these display the data in soft or hard copy. The cables and connectors that join it all together. There are three types of hardware. These are: 1) INPUT DEVICES These are the tools used to enter data, commands and information into the computer’s central processing unit (C. P.U).
he most common input devices are: Keyboard This is the most common and widely used input device. It is used to key in data. Touching or pressing a key sends an electronic signal to the computer that interprets it as a character or function. Some special keyboards include touch sensitive keyboards, braille keyboards, mobile phone keyboards and Large-keyed colour coded keyboards, amongst others. Keyboards are divided into four main areas are: ? Function keys across the top ? Letter keys in the main section ? A numeric keypad on the right
? Cursor movement and editing keys between the main section and the numeric keypad. Mouse This is a pointing device used to control the movement and position of the cursor by moving the mouse around on a flat surface such as a desk. The standard mouse comprises casing, buttons and base. As technology has developed, the mouse has evolved from its original design and now come in different styles to suit different requirements. Scanner This is an input device that reads words or graphics from a printed page and translates the pattern of light and dark (or colour) into a digital signal the computer can store and manipulate.
The most common scanner is the flatbed scanner that works quite like a photocopier. Hand-held scanners are still used but, as flat board scanners are now quite inexpensive, their use is diminishing. They are only a few centimetres wide and this limits the amount of information that can be scanned to small areas. Digital Camera This looks just like a traditional camera but instead of recording an image on film, light intensities are converted into digital form that can be stored on a disk as a data file, similar to a word or Excel file.
The digital camera is now more commonly and widely used than traditional camera because pictures can be previewed and if they are not good enough can be DELETED. Joy Stick These are used mostly when playing computer games. The handle in the centre of the joystick moves an object on screen and translates movements of the hand and fingers into the motion on a computer screen. Rollerball This is also known as a tracker ball. It is an upside down mouse that allows the user to point to selected items on screen. The user rotates the roller ball with his/ her fingers instead of pushing a mouse around a desktop.
It requires very little space to operate and is commonly built into laptop computers in place of a normal mouse. Microphone This input device is sound sensitive and the microphones used with computer are the same as any other type of microphone. Because it is used mostly with voice recognition that translates spoken words into digital signals for the computer, it makes it possible to operate a computer without using any hands- it’s hands free. 2) OUTPUT DEVICES These are the devices used for retrieving information from the computer either through sight or hearing. The most common output devices are:
? Video Display Unit (VDU) ? Speakers ? Printers Video Display Unit This is otherwise known as monitor. It displays images generated by the computer’s video adapter. They come in different sizes- 15, 17 19 and 21 inches. The sharpness or clarity of the image on the VDU is determined by its resolution. The resolution is measured in pixels. When it is looked at closely, it is obvious that the image is made up of tiny dots. Each dot is known as a pixel. The image made on the screen is known as the frame. There are many types of VDU and the most common type is the flat screen VDU. Printers
This gives the permanent (hard) copy of the information on screen. Most Pc’s use a laser or ink-jet printer. The speed of the printer is counted in dots per inch or DPI- the higher the value, the higher the value, the faster the speed (and the greater the cost). There are many types of printers some of which are: Inkjet printers Laser printers Dot-matrix printer Speakers Most PC’s are fitted with a small internal speaker that will bleep to draw attention to the user for example if the wrong keys are pressed. On multimedia PCs additional speakers are attached to the computer to add better quality sound.
The amplifier driving external speakers is built into the sound card or into one of the speakers themselves. The speaker is a very important part of the computer’s hardware because not only does it alert you when something has gone wrong, it can also be used to listen to music and helps blind people because the results of their instructions to the computer can be read out to them. 3) STORAGE DEVICES These are those devices that save data in the computer’s hard drive or a disk drive. A disk drive is a storage device that transfers data to and from a magnetic or optical disc. The main storage devices are: ?
The hard drive? The floppy drive ?The CD- ROM drive ?DVD drive The hard drive This is the storage area (like a filing cabinet) where all the applications software used and created documents are kept. It is the main memory of the computer. They (hard drives) are measured in gigabytes (GB). Expensive computers usually have the largest hard drive (over 30GB). The hard drive houses the hard disks that are flat, round and rigid plotters that provide faster access to data than floppy discs and that are capable of storing much more data. Because they are rigid, they can be stacked such that one hard disc drive can access more than one platter (hard disk).
They come in sealed units that protect them from contaminants (like dust), which might interfere with the close head-to-disk tolerances. The floppy drive This is a removable storage area that enables files to be saved on a floppy disk so that data files can be taken between home and school or college and you make back-up copies of data files as a security measure. They are round, flat and made of a substance called Mylar. They have a magnetic surface that allows the recording of data and are covered in a protective plastic shell. The disc turns in the drive allowing the read/ write head to access the disk.
The CD-ROM drive This uses the same technology as CD music disks and CD players. A laser beam reads the data from an optical disk rather than a magnetic disk. A typical CD holds around 650MB of data, which is equal to 450 1. 4MB floppy disks. The CD- drive has a read only memory, which means you cannot alter or store data. However, CD writers are now available that enable data to be written to CD. These enable you to make copies of music on CD and are increasingly being used for backing up hard drives. CONNECTORS, NETWORKS, NETWORK PROTOCOL Cables connect the different components of a computer system.
When a system is set up it is important to check the input or output devices are connected to the main processing units correctly or the computer won’t operate. The former means of connecting the computer were through Ports. Ports are sockets at the back of the main processor causing, which are used to attach the peripheral devices e. g. printer, monitor, keyboard, mouse and so on e. t. c. Cables from each peripheral plug into ports allowing data to be sent and received from the microprocessor. There are two types of ports Serial ports: – Transmits data one at a time.
They are known as COM1, COM2 and are referred to as male connectors because they have pins Parallel ports: – This on the other hand transmits data in bytes, which is much faster than serial. Parallel ports are LPT1, LPT2 and are designated female connectors because they have receptacles for the pins. Nowadays there are new connectors for computers. They are: – ?USB (Universal Standard Bus) Allows a wide variety of computer peripherals to be easily connected to most PC’s, Windows 98/2000 and this is a newfound saviour from parallel and serial ports.
A compact USB port provide more superior (better quality) data transfer speed more than 99 times faster and compared to 25-pin parallel and DB-9 serial ports found on old updated computers it is fast and easy. Nowadays, people mostly use USB interface in peripheral connections such as USB- image scanners, colour inkjet printers, joysticks, and memory card readers. USB is used as the external Plug and Play standard for low cost, home computing peripherals. Plug and Play is a standard USB follows very effectively. Important Features of the NI USB-232 and NI USB-485 Serial Converters.