Class 9 Computer: Computer Hardware (Lesson 2)

Computer hardware includes the physical parts of a computer, such as the Case, Central processing unit (CPU), monitor, mouse, keyboard, computer data storage, graphic cards, sound cards, speaker, motherboard, printer, etc. 

By contrast, software is the set of instructions that can be stored and run by hardware. Hardware is so-termed because it is "hard" or rigid with respect to changes, whereas software is "soft" because it is easy to change.

Hardware is typically directed by the software to execute any command or instruction. A combination of hardware and software forms a usable computing system, although other system exist with only hardware.

Input Device - Devices that send data or instructions into a computer

Input computer hardware is devices that translate data into a form the computer can process. Normally, it translates into binary code that can be process by computer to translate words, sounds, numbers, and images. The input computer hardware are like keyboard, source entry devices such as scanner, pointing devices which is mouse, and others.

1. Keyboard

Keyboard is use to convert letters, numbers, symbols, and characters into electrical signals which commonly binary signals that can be process by computer. Keyboard is the most common in inputting information or data into a computer. Basically keyboard is build-up of human interface device which is layout of buttons.

Generally, keyboard work with basic mechanical which keyboard relies on springed keys being pressed down to complete an electrical circuit. This circuit will then transmit a binary signal that to be processed by computer to represent the key pressed. 

Types of Keyboard

• Standard 

Standard alphanumeric keyboards commonly consists 104 - 108 key press. It including alphabetic characters, punctuation symbols, numbers and variety of function keys. Nowadays, the enter key also comes with variety size and shaped. keyboard also build with additional key such as Windows keys.

• Laptop Size

Normally, they consists of 80 - 85 key for laptops. the manufacturer minimize the keys and merge it together and shorter travel distance for keystroke. It makes laptop keyboard small and compact size that suits with size of laptop.

• Wired Keyboard

Wired keyboard is actually same characters as the standard keyboard. This type of        keyboard are used wired with USB port to transmit the electrical signal to be process by         computer.

• Wireless Keyboard

Wireless keyboard one of new technology improvement which is it used infrared technology, radio frequency technology, or Bluetooth to transmit signals rather than wired. it can be transmit in long distance compared to wired which it has limitation due to the length of the wired. In electronic market, usually it comes with a set that consists of wireless keyboard and wireless mouse. 

Pointing device is an input interface that allows user to control and provide data to the computer using physical gestures by moving a hand-held mouse or similar devices. The use of pointing devices is to control the position of the cursor or pointer on the screen and allow the user to select options displayed on the screen. Commonly pointing devices are mouse, and it including the pointing stick, touch pad, digitizer, and others.

Types of Pointing Device

• Mouse

Mouse consist of two type which is mechanical mouse and optical mouse. the mechanical builds with a ball inside the mouse and it touches a surface and rolls with the mouse. The optical mouse use laser beams and special chips to encode data for the computer.

• Trackball

Trackball is a movable ball that mounted on top of the stationary device. The ball give an advantage for good locations where a mouse can not move around enough. It widely user in design and manufacturing industries.

• Touchpad 

Touchpad are slightly same as touchscreen, but taouchpad only can be use in their provided space, commonly square or rectangle in shape. It works by slide your finger over their small flat surface, and tapping your finger on the surface to click an options. It widely use in laptops. 

• Pointing Stick

Pointing stick is a pressure-sensitive small nub used like a joystick. It located between            the keys on a laptop keyboard that allows the user to control the pointer by directing the    stick with one finger. Commonly found in between 'G' and 'H' key, and also at below the          spacebar.

• Touchscreen

Touchscreen is a device embedded into the screen of the LCD monitor screen. It use with an interaction between the screen by physically touch of finger. It very sensitized to detect touch on the screen. Generally used in ATMs, information, kiosks, reservation kiosks, voting machines, smartphone, tables, laptops, and e-books.

• Multitouch Screens

Multitouch screen is an device that allow two or more fingers or other gestures such aspinching motions to be recognized as input at any one time. It allows pinching and stretching gestures on the screen to control zooming.

Source data-entry devices is devices that create machine-readable data and feed it directly into the computer without keyboard or mouse. There are much electronic devices that acts as source data-entry such as scanner, cameras, bar-code reader, electronic chips, and audio.

Types of source data-entry devices:

• Scanner

scanner is a electronic imaging device that use light-sensing equipment to translate images of text, drawings, and photos into digital form to computer. The resolution refers to the image sharpness and it measured in dots per inch (dpi). The flatbed scanners work like photocopies which the image is placed on the glass surface, and then scanned and sent into computer in form of image file.

• Bar-code readers

Bar-code readers is an electronic device for reading printed barcodes usually on a product to know their information which their price. It consists of light source, a lens and light sensor that translating optical impulses into electrical signal. the code type can be in 1D, 2D, or 3D. 1D codes regularly vertical stripes that can holds up to 16 ASCII characters. 2D is different size rectangles that can hold 1000 to 2000 ASCII characters. 3D is 'bumpy' code that differentiates by symbol height, and commonly used on metal, hard rubber and other rough surfaces.

        

                                                1D codes                                                          2D codes

                         

3D codes

• Radio Frequency Identification (RFID)

RFID works based on an identifying tag bearing a microchip that contains specific code numbers or data these code numbers are read by the radio waves of a scanner linked to a computer database. active RFID tags have their own power source and can transmit signals over a distance to a reader device. Passive RFID tag have no battery power of their own and must be read by some sort of scanner. RFID tag of both types are used for a wide range of purposes and are starting to replace bar codes in many situation. The use of RFID is more efficient rather that use bar codes.

RFID tag behind information tag

RFID scanner

• Mark Recognition Readers

         1. MICR - magnetic-ink character recognition

             This type of mark recognition use special magnetized inks that only can be read by a              special scanner that can read this magnetic ink. It commonly can be found at the                     bottom of bank checks.

         2. OMR - optical mark recognition

 The optical mark recognition (OMR) are use a special scanner that can reads bubble              or pencil marks. This optical mark recognition (OMR) are generally use in educational              where it use to evaluate standardized test such as the SAT and GRE.

           3. OCR - recognition

               The optical character recognition is a scanner that convert scanned text from                           images (pictures of the text) to an editable text format. The scanner are design alike                as standard images scanner and also pen shape design.

• Images Capture Devices

          1. Digital Cameras

             

             The digital cameras capture images by using a light-sensitive processor chip to                     capture photographic images in digital form and store them on a small disk (SD card              or microSD card) in the camera or on flash memory cards. Most digital camera today              equip with USB port that can be easily connected to a PC and also smart TV. Camera              of smartphones also can be consider as digital camera.

        2. Webcams

            Webcams is a video cameras that attached to a computer to record live moving                        images then post them to a website in real time. Today, most laptop are already equip             with webcams. Webcam can be attached externally by USB connection. Webcam can             be classified in two categories which is;

            

            - Frame-grabber video card

              This type of webcams can capture and digitize 1 frame at a time

            - Full-motion video card

              This type of webcam can capture and convert analog to digital signal at rates up to                  30 frames per second. It looks like a motion picture. 

• Audio-Input Devices

         Audio-input device is a device that capture analog sound waves and convert it into                 digital signal that can be process and store by computer. There are two way to digitize             audio, and commonly via microphone.

         - Sound Board

            It is an add-on board in a computer that converts analog sound to digital sound, store,             and plays it back to speakers or amp.

        - MIDI Board

          MIDI is stands for Musical Instrument Digital Exchange. It widely used in a standard for           the interchange between musical instruments, synthesizers, and computer.

        - Speech Recognition Systems

           The speech recognition systems use microphone or telephone as medium of input                   devices. It converts a person's speech into digital signals by comparing against                       200,000 or so stored patterns. This devices are actually really helpful where it very                   useful in situation where people need their hands free such as car radios, and others.              It also an advantage for disability user which they may can not handle the other input               devices.

• Sensor

          Sensor is one of input devices that collect specific data directly from the environment              and transmit it to a computer database. It can be used to detect speed, movement,                  weight, pressure, temperature, humidity, wind, current, fog, gas, smoke, light, shapes,              images, earthquakes, and others that beyond human limitations.

Sensor (proximity sensor)

• Biometric-Input Devices

         Biometrics is the science of measuring individual body characteristics, then using then             to identify a person through a fingerprint, hand, eye, voice, or facial characteristics. For          example, laptop nowadays equip with biometric sensors that read user facial before                 allowing access to networks. It also can be acts as safety precaution to avoid thief.                 Besides that, airport and building security systems also use biometrics systems.

Output Hardware

The fundamental of output computer hardware is same as the input computer hardware, but they are vice versa. Output computer hardware are translating the information processes by computer into form that humans can understand such as words, sounds, numbers, and images. Generally, it translates the binary code that produced by computer. Today, there are much output computer hardware in the market such as variety of monitors, speakers, printers, and others. Softcopy Softcopy is an electronic copy of some type of data, such as file viewed on a computer's display or transmitted as the mail attachment. It also including audio or voice form and images. This kind of output is not tangible, it means that it can not be touched. You can touch disk on which programs are stored, but the software itself is intangible. The most popular and important softcopy output devices are the monitor or display screen to show all kind of software either database, images, and etc. There are few features of display screen that need to consider:- Screen Size           The active display area is the size of a computer screen measured diagonally from                  corner to corner in inches. Desktop computer screen are commonly 15-30 inches,                  laptop between 12-18 inches, tablets are 8.4-14.1 inches and smartphones 2.5-4.1                  inches. Nowadays, smart TV also  can be use as display screen of a computer by                  connected the HDMI port. Aspect Ratio          The aspect ratio is the proportional relationship of a display screen's width and height.             The standard displays have a 4:3 aspect ratio where 4 units wide to 3 units high, and             wide-screen displays have 16:9 or 16:10 aspect ratio. The high aspect ratio, more                 smooth images can be displays. Screen Clarity 1. Dot pitch (dp) Dot pitch (dp) is the amount of space between adjacent pixels where square picture            elements on the screen. The closer the pixel, the crisper the images. The best dot                  pitch (dp) are .25 dp or better. 2. Resolution The resolution is refer to the image sharpness of the screen. There are directly                     proportional between pixel and resolution. When more pixels are used, the better the              resolution will be. It expressed in dots per inch (dpi). 3. Colour Depth Colour depth also known as bit depth. Colour depth is the number of bits stored in a             dot (pixel). The higher the stored number in dot, the more true the colours. For                         example, the 24-bit colour depth is better than 8-bit colour depth, but it needs more               video card memory for supports.  4. Refresh Rate Refresh rate is the number of times per second the pixels are recharged. This mean,            when a higher rate gives, the less flicker occur.

Hardcopy is a printed copy of information from a computer. Sometimes it refer to as a printout, so it called hardcopy because it exists as a physical object. Hardcopy is tangible output that usually printed. The principal examples are printouts, whether text or graphics, form printers and also films including microfilms and microfirche is also considered as hardcopy output. 

Printers

Printers are the most user use to produce an hardcopy output which is printed paper. Printers can print text and graphics on paper or other hardcopy materials. Printers resolution is measured by dots per inch (dpi): 1,200 times 1,200 is the most common for microcomputers. The printers are classified as two categories either impact printers or non -impact printers. The Impact printers is dot-matrix printer that can print by striking the paper directly. Non-impact printers are such as laser printers and inkjet printers that do not have direct contact with the hardcopy medium.

Types of Impact Printers

• Laser Printer

          Laser printer is a dot-matrix printer which creates images with dots. however, as in a              photocopying machine, these images are produced on a drum, treated wirt an                          electrically charged inklike toner which powder compound, and then transferred from              drum to paper. It runs with software called a page description language (PDL), which              tells the printer how to lay out the printed page and support various fonts. Laser pinter              normally have their own CPU, ROM, and memory to stored information data for a while           before printing on paper to prevent the lost of data while printing session. The                          graphics-heavy document required much more memory compared to texts or                          documents.

• Inkjet Printer

Inkjet printers work by spray ink onto paper small that electrically charged droplets of ink         from four or more nozzles through holes in a matrix at high speed. Alike laser and dot-           matrix printers, inkjet printers form images with little dots which produce better output.            Inkjet printers commonly have a dpi of 4,800 times 1,200 makes it can spray ink onto            the page a line at a time. They have high quality in both high-quality black and white                text and high-quality colour graphics.

Inkjet printer process

Example of inkjet printer

Types of Non-Impact Printers

• Thermal Printers

          Thermal printers is a low to medium resolution printers that use a type of coated paper           that darkens when heat is applied to it. It typically used in business for bar-code label              applications and for printing cash register receipts. 

Thermal printer process

Example of thermal printer

• Thermal Wax-Transfer Printers

          The thermal wax-transfer printer are use to print a wax-based ink onto paper. After it              becomes cool, the wax adheres permanently to the paper. because of their                              waterfastness, these labels find uses in industrial label printing.

Thermal wax-transfer process

Example of thermal wax-transfer printer

• Photo Printers

         Photo printer is a specialized machines for printing continuous-tone photo prints with             special paper and colour dyes. Usually photo printer are much expensive compared to             others.

Example of photo printer

Multifunction Printers

The multifunction printers are actually is a combination of all printers where they can do printing, scanning, copying and also faxing. The advantages by using this kind of printers are cost less and take up less space to stored rather than buying the four separated printers. But, it comes a problems when one component are malfunction, the other will malfunction also. Most office are using this kind of printers to do their jobs easily.

Example of multifunction printer

Plotters

Generally, plotters are used in designed for large-format printing where they are specialized output device designed to produce large high-quality 3D graphics in a variety of colour. It commonly used in fields of  architecture, engineering, and map-makers. Plotter can be classified into three which are pen plotters, electrostatic plotters, and large-format plotters. Pen plotters refer of use one or more coloured pens. Electrostatic plotters are lie partially flat on a table and use toner as photocopiers do. Large-format plotter are large-scale inkjet printers used by graphic artists.

 Example of plotters

Mixed Output: Sound, Voice, & Video

Mixed output is a combination of output where sound, voice & video. This combination can be found when you are watching movie where there a surround sound, better voice & high-quality of video displays. Sound Output Sound output such as speakers can produces digitized sound, even 3D sound and surround sound. In computer hardware, you need sound card to allow the computer convert digital signal into sound waves. In order to get high-quality sound, good speakers can be used to improve sound waves. Example of sound output Voice Output Voice output is the digital data that being convert by computer to produce speechlike sounds. It commonly found in phone trees, cars, toys and games, GPS systems, and TTS (text-to-speech) systems for hearing-impaired people. The toys 'speak' when being pressed Video Output Video output is a photographic images played quickly enough to appear as full-motion. To achieve that, it require powerful processor and high video card. The video files are large, so a lot of storage is needed. For example, video conferencing is a form of video output. Example of video conferencing situation