Understanding Computer Hardware: Input, Output, Processing, and Storage Devices, Essays (high school) of Computer science

Download Understanding Computer Hardware: Input, Output, Processing, and Storage Devices and more Essays (high school) Computer science in PDF only on Docsity! Hardware and Software A computer system is made up of a combination of hardware and software. Hardware: All of the electronic and mechanical equipment in a computer is called the hardware. Examples include: • Motherboard • Hard disk • RAM • Power supply • Processor • Case • Monitor • Keyboard • Mouse Software: The term software is used to describe computer programs that perform a task or tasks on a computer system. Software can be grouped as follows: • System software: These are the programs that control the operation of the computer system. Operating systems and utility programs are the most common. The Operating System starts the computer, provides a user interface, manages the computer memory, manages storage, manages security and provides networking and internet facilities to mention a few of it’s capabilities. There are many OS’s on the market including Microsoft Windows XP, Microsoft Windows Vista, Apple OS X , Unix and Linux. Windows is by far the most commonly used OS in the world, but Linux in particular, is making inroads into this dominance. Utility programs perform maintenance tasks on the computer system. This includes file management programs, uninstall programs, disk scanners and defragmenters, backup utilities, antivirus etc. These can be included in the OS or purchased separately. Device drivers are programs that control particular hardware devices. They are supplied with new hardware and must be run so they the hardware can communicate with the OS. They are supplied with printers, graphics cards, scanners etc. • Application Software: This software is used to do non-system based tasks. Categories include business software, engineering software, medical software, games etc. • Sometimes, application software packages are grouped together to form productivity suites. Examples include Microsoft Office and OpenOffice. These combine word processing, spreadsheet, database and presentation software with a common interface making then easier to learn. The Adobe Creative suite combines Adobe Photoshop, Adobe Illustrator, Adobe InDesign etc. as an all-in-one graphics and web design suite. As well as common interfaces, these suites offer great compatibility between the applications. System Unit Devices The Processor (CPU) A processor is an integrated circuit (IC) supplied on a single silicon chip. All of the components and pathways necessary for the movement of data around the processor are etched on this single chip. The processor’s function is to control the activities of the computer system. A computer program is made up of instructions and when the program is run, the processor is responsible for carrying out these instructions in an orderly fashion. The type of instructions the processor can execute includes: • Arithmetic instructions - It carries out all the addition, subtraction, multiplication and division requested by computer programs. • Logical instructions - It can make decisions by comparing data and acting in a particular way depending on the result. • Move operations - It can move data from place to place within the computer system. This could be from memory to the processor for addition or from memory to a printer or disk drive etc. The speed of a processor is measured in megahertz (MHz) or Gigahertz (GHz). This is the speed of the system clock (clock speed) within the processor and it controls how fast instructions can be executed: • 1 MHz - One million clock ticks every second • 1 GHz - One billion clock ticks every second This means that if one instruction was executed every clock tick, a 3GHz processor could execute three billion instructions every second. AMD Processor The two main computer processor manufacturers are Intel and Advanced Micro Devices (AMD). These two companies produce almost all of the processors used in desktop and notebook computers. • Intel - Intel makes the Pentium and Centrino ranges of processors. • AMD - AMD makes the Athlon and Turion ranges of processors. The performance of these chips relative to each other is forever changing and it would be difficult to claim one is better than the other in the long term. The latest trend in processor manufacture is to essentially put more than one processor on a silicon chip. These multi-core processors can have two, three or four processor cores on a single chip. This obviously vastly increases the performance of the computer system as long as the programs run on the systems can take advantage of the multi-cores. Another important factor in processor choice is the amount of power a processor consumes. This is not critical on a desktop computer but is critical on a notebook computer. AMD and Intel have developed a range of processors optimised for mobile computers. The Turion and Centrino processors use very little power to maximise battery life and are optimised for wireless networking, factors that are very important in mobile computing. They also use Speedstep or Powernow technology to regulate the processor power to the system requirements. Wordprocessing needs less processor power than CAD and the system can adjust the processor speed to suit the program being run. This saves power and produces less heat. In a notebook computer, this is a huge advantage. Random Access Memory (RAM) Known as primary storage, it is the main working memory of the computer system. Data and programs currently in use are held in RAM. It is called random access because data can be accessed in any order. If you are working on a drawing in Solidworks, the Solidworks program and the drawing under construction are both held in RAM. RAM is volatile which means that when the computer is turned off, the contents of RAM are lost. This is why it is essential to save your work on a regular basis. Because of the volatility of RAM, most software programs have an autosave feature to prevent the total loss of your work. RAM is made in the form of integrated circuits (IC’s) in the same manner as a processor. These IC’s are placed on a circuit board to produce a memory module. The most common RAM technology is dynamic random access memory (DRAM). In this technology, a transistor and a capacitor are paired to store one Bit (binary digit) of data. In essence, if the capacitor is charged, a binary 1 is stored and if it is discharged, a binary 0 is stored. (see the section on data representation for more on binary data). The transistor acts as a switch to allow the capacitor’s state to be changed as required. There is a problem with this technology. As soon as the capacitor is charged, it begins to leak. As a result, the charge in the capacitors must be continually refreshed or they would leak to binary 0’s resulting in corrupted data. This continuous refreshing is performed about 80 times per second and drastically slows down the speed at which main memory can be written to and read from. IC’s Memory Module The Motherboard Often called the mainboard or system board, it is the main circuit board for the computer system. Every device in the computer system will either be part of the motherboard or connected to it. The motherboard shown above is an Asus A8V-VM. This board is designed for AMD processors. The main parts of the motherboard are: 1 Processor socket This socket is an AMD 939 pin socket. It is designed for the Athlon X2 processor. Different processors require different sockets and a motherboard must be chosen to suit the processor intended for use. 2 Memory sockets The board has four memory sockets and accepts DDR 266/333/400MHz memory up to a total of 4GB 3 Power connector The power supply connects here and supplies appropriate power to the different components on the motherboard. 4 Primary IDE Hard drives can be either IDE (Integrated Drive Electronics) or SATA (Serial Advanced Technology Attachment). If an IDE hard drive is being used, it should connect to this socket. 5 Secondary IDE This could be used to connect a second IDE drive. This could be a second hard drive or an Optical drive - DVD or CD drive. 6 CMOS RAM chip A DRAM chip used to store the date and time and any user settings added to the setup screen. Complementary metal oxide semiconductor is the material the chip is made from. 1 2 7 6 8 3 4 5 10 9 11 12 13 14 15 21 18 17 16 20 19 22 24 23 22 7 CMOS battery Because the CMOS chip is a DRAM chip, it is volatile and would loose data when the computer is switched off. The battery preserves the data in the CMOS RAM chip when the computer is powered down. 8 SATA connectors Used to connect SATA hard drives and optical drives 9 BIOS chip Basic Input/Output System. A chip holding the start-up routine for the computer system. It runs a program to test the hardware of the system. It the test is successful, a single beep is sounded. If not, a series of beeps are sounded and these beep patterns can be used to identify the failing component. 10 Southbridge chip Forms the chipset with the northbridge. Between them they control the buses on the motherboard. Buses are the data pathways between the motherboard components. The southbridge controls the slower buses like the IDE bus, SATA bus, USB bus etc. 11 Northbridge chip Controls the faster buses on the motherboard. These include the front side bus (between the processor and main memory) and the graphics bus. 12 PCI sockets Peripheral Component Interconnect sockets used to connect expansion cards like modems, network cards, TV tuner cards etc. 13 FDD connector For connecting a floppy disk drive. 14 PCI-Express The graphics card connects here. Other motherboards have an AGP (accelerated graphics port) slot. 15 Super I/O chip Controls the serial, parallel, mouse and keyboard ports at the back of the computer system. 16 Network chip Controls the network port at the back of the computer 17 Audio ports For connecting speakers, microphones etc. 18 USB ports The current standard for connecting peripherals. 19 Network port Used to connect the computer to a network 20 Video port Connect the monitor to this port if a PCI-Express graphics card is not being used. 21 Parallel port Largely obsolete. Used to connect printers and scanners. 22 Serial port Largely obsolete. Used to connect external modem etc. 23 PS2 ports The keyboard connects to the purple port and the mouse connects to the green port. Largely replaced by USB. 24 Audio chip Controls the onboard audio system. Chipset The flow of data around the computer is controlled by the Chipset. This consists of two chips: • Northbridge: This chip controls the flow of data between memory and the processor. It also controls the flow of data between the processor and the graphic's card. • Southbridge: This chip controls the flow of data to the slower devices. These include USB, IDE, SATA, LAN and Audio devices. It controls the PCI slots and the onboard graphics chip. It delegates control of the keyboard, mouse, parallel and serial ports to the Super I/O chip. Processor RAM Northbridge All Memory Southbridge IDE SATA USB LAN Audio Super I/O Keyboard Mouse Parallel Serial BIOS Graphics Slot PC-Express or AGP PCI Slots Onboard Graphics Ports and cables going off board Front Side Bus Memory Bus Graphics Bus Internal Bus PCI Bus PCI Bus Low Pin Count Bus Ports Computer ports are interfaces between peripheral devices and the computer system. They are hardware devices built into the motherboard or on expansion cards. They are often built into the front of the computer chassis for easy access but will be cabled back to the motherboard. Serial port Although more or less obsolete, they are still included in new systems. The serial port is a 9-pin port. Windows calls them Com ports - Com1, Com2 etc. Mice and external modems were connected to these ports. They are turquoise in colour. Parallel port This 25-pin port is used to connect printers, scanners, external hard disks, zip drives etc. to the computer. It is burgundy in colour and windows refers to them as LPT ports - LPT1, LPT2 etc. The original port only supported single direction communication but the modern parallel ports can support bi-directional communications. This is essential for reporting ink levels etc. in printers. Ports at the rear of the computer Ports at the front of the computer Video port Used to connect a monitor to the computer system. There are two types: • VGA port: This is a 15-pin port and is blue in colour. It is an analogue port and is being replaced by the DVI port. • DVI port: This is white in colour and is a digital port. This means that no conversion is necessary between the computer and the monitor and that means that images can be produced more quickly on the monitor. PS/2 port PS/2 ports are used to connect keyboards and mice to the computer. The keyboard port is purple and the mouse port is green. USB port The universal serial bus was intended to replace Serial, Parallel and PS/2 ports with a single standard. 127 devices can be connected to a single USB port and computers are often supplied with six to ten ports. USB is hot swappable which means that devices can be connected and disconnected without turning off the computer system, something that should never be attempted with parallel or serial devices. There are different USB standards in use: • USB 1: This is the original standard and can transfer data at 1.5MBps. This is too slow for external hard disks with capacities of 500GB or more. • USB 2: This is forty times faster than USB1 and has a data transfer rate of 60MBps. This is the current standard. • USB3: this is tem times faster than USB2 and 400 times faster than the original USB1. it has a data transfer rate of 600MBps and will be common on new computer systems in 2009. Firewire port FireWire (IEEE 1394) is a technology introduced to the computer world by Apple. There are two versions available and a third is planned: • FW 400: This can transfer data at 400Mbps which is 50MBps. This makes it similar in speed to USB2. • FW 800: This can transfer data at 800Mbps which is 100MBps making it considerably faster than USB2. • FW S3200: This will transfer data at 3200Mbps which is 400MBps. It is intended to compete with USB3. The main difference between USB and FireWire is that USB is host based and FireWire is not. USB devices must be connected to a host computer while FireWire devices can be connected to each other without using a computer. Modem port Technically known as an RJ11 port, it is the common telephone socket used in Ireland. Modems will usually have 2 ports side by side. The port marked Line should be connected to the wall socket while the port marked Phone can be used to connect a telephone. The phone can then be used he when computer is offline or if a V92 modem is used, the Internet can be put on hold while the incoming call is taken. A graphics card will have it’s own processor and memory built in. The faster the processor and the more memory a graphics card has, the faster and more even the display will be. If the on screen image is jerky or blurred, the graphics card is not good enough for the job. The main parts of a graphics card are: Computers are often supplied with integrated graphics cards. This means that the main memory must be used to control the graphics system and the main processor must supply most of the processing power. This is perfectly OK on an office computer where word-processing etc ate the main activities. Introduce CAD etc. and the system becomes unusable. 3 1 2 4 5 1 Processor and fan This allows the graphics card to manage it’s own processing and makes it almost independent of the main computer processor. 2 Board connector This will be either AGP or PCI-Express 3 Memory The graphics card does not need to use any main memory as it has it’s own. This makes it much faster. Most new graphics cards use DDR3 memory. Up to 1GB of DDR3 memory is now available on graphics cards although this makes them as expensive as most computer systems. 4 DVI connector Digital output is supplied through this port. If a digital monitor is present, this is the best option as no conversion is required. 5 VGA connector Analogue output is provided through this port. If you have an analogue monitor, you must use this port. If you have a digital monitor, it is best to use the DVI port as the graphics card works in digital and must convert to analogue to use the VGA port. Sound card In recent years, computers have become entertainment centres with media centre operating systems controlling TV and video. The need for good quality sound and even surround sound has made it almost standard on most computers. Most computers are supplied with an integrated sound system and this is sufficient for most applications. A sound card can be fitted to an empty PCI slot and the integrated chip turned off if the extra features of a card are required. The main functions of a sound card are: • To use a DAC (digital to analogue converter) to prepare audio for speakers etc. • To use an ADC (analogue to digital converter) to convert the audio coming into the computer. A sound card can be connected to the following: • Analogue input devices - Microphone, Radio, Tape deck, Record player etc • Headphones and speakers • Output to tape etc. 1 2 3 1 PCI connector Used to connect the sound card to a PCI slot on the computer motherboard. 2 MIDI socket Musical Instrument Digital Interface port is used to connect digital musical instruments to the computer. This port is no longer supplied on integrated systems and if one is needed, the only option is to fit a sound card to the computer system. 3 Audio jacks These are used to connect microphones, speakers, stereo systems etc to the computer. Network card A network card is designed to allow computers participate in a computer network. This can simply be a home computer connected to a Broadband connection or a number of computers connected together to share resources. Network capability is included on most new motherboards, but a different network card can be added if required. Network cards can offer wired or wireless connection. They can fit into a PCI slot on the motherboard or even connect to a USB socket. Modern notebook computers have an internal wireless network card as well as the standard wired card. The standard used in the majority of networks is called Ethernet. This covers wired and wireless networks. Ethernet is controlled by the Institute of Electrical and Electronic Engineers (IEEE) and there are a number of standards in use in wired networks: • Fast Ethernet: A wired standard with a transmission speed of 100Mbps. This is the most common standard and integrated network chips are usually of this standard. • Gigabyte Ethernet: A wired standard with a transmission speed of 1000Mbps. This is 10 times faster than fast Ethernet and is becoming more common. Wired Ethernet is available as a PCI card for desktop computer systems, a PC card version for notebook computers and a USB version for either of the above. The wireless standards include: • The B standard: Introduced in 1999, this standard offers a transmission speed of 11Mbps. It has an effective range of 30 Metres. • The G standard: This was introduced in 2003 and offers a transmission speed of 54Mbps. It has a useful range of approximately 30 Metres. • The N standard: Introduced in 2006, this is the latest wireless standard and it offers a transmission speed of 540Mbps. It has an effective distance of 50 metres. PCI PC card USB • SATA (Serial Advanced Technology Attachment) allow faster data transfer speeds than IDE drives and as such, will eventually replace them. There is no master/slave arrangement with SATA and each drive has it’s own cable. The cables are much smaller and allow better air circulation in the system unit. The motherboard connectors are shown below. Hard disk capacities range from 100GB to 500GB and some computer manufacturers are now offering computers with SATA drives of 1TB (Terabyte - 1000GB). Hard disks have rotational speeds of between 7,200rpm and 15,000rpm. This effects the transfer rate - the amount of data that can be written or read from a disk per second. Transfer rate varies from 50MB/s for the 7,200rpm drive to 200MB/s for the best 15,000rpm drives. External hard disk drives are available as IDE or SATA and can be mains powered or host powered. Host powered drives receive their power from a USB port and are useful with notebooks as well as desktop computers. Hard disk drives are also now found in video recorders, digital music players, digital camcorders, digital cameras and mobile phones. SATA Cable SATA IDE Host Powered Mains Powered 2½ inch Notebook Drive 1 inch Microdrive Microdrive Optical drives Optical drives use laser technology to sense pits and lands mechanically pressed into a polycarbonate disk. These pits and lands represent the binary 0’s and 1’s and so can store computer data. A thin layer of metal is added to the polycarbonate disk to reflect the laser light. As the disk rotates, the laser senses the pits and lands and reads the data from the disk. The laser only needs to operate at a single intensity as it only scans the surface of the disk to detect the pits and lands. This is the system used on all mass produced optical disks. CD-R (blank CD’s) disks obviously cannot be mechanically pressed in a computer and as a result, a different method must be used to encode data onto these disks. In a CD-R (write once) disk, a layer of Dye is used to encode the binary data. The optical drive must have a laser with two intensities. The dye layer in it’s natural state can be penetrated by the laser light and the reflective layer reflects the light back to the sensor in the optical drive. If the laser is set to the higher intensity, it will turn areas of the dye layer opaque on contact (burn) and these areas will not allow laser light to penetrate. This situation mimics the pits and lands produced on the mechanically pressed disk and data can be stored on the disk. The CD-RW (re-writable) disk is similar but the laser must have three light intensities. The third and highest intensity is required to turn the burned areas of the dye layer back to their original condition. The dye layer can now be re-burned to hold new data. The three laser intensities are: • Intensity 1: Read data • Intensity 2: Burn data • Intensity 3: Erase data In actual fact the laser can be set at multiple intensities depending on the disk type being burned. The CD-R disk has a capacity of between 650MB and 800MB. Pit Land Polycarbonate Label Reflective metal layer Dye layer DVD disks are similar to CD disks except that they can store a lot more data. DVD has several formats and compatibility issues. DVD also introduces layers and sides, where more than one dye layer is formed on the disk, and sides, where the disk can hold data on both sides. Each layer of a DVD can hold 4.7GB of data. The possibilities are: To make double layer disks work, two metal reflective layers are used. The first is gold based and can be penetrated by the laser once a certain intensity is reached. Below this intensity it reflects. The second reflective layer is aluminium based and is totally reflective. By varying the laser intensity, either layer can be read or burned. The double sided disk is two of the above glued back to back. DVD formats: There are significant differences in the DVD-R standard and the DVD+R standard making them incompatible with each other. They vied with each other to become the standard and neither has won. The result has been that manufacturers have produced DVD±R drives capable of reading and writing to both standards. Number of sides 1 1 2 2 Number of layers 1 2 1 2 Disk capacity 4.7GB 8.5GB 9.4GB 17GB Polycarbonate Label Total reflective metal layer Dye layers Semi reflective metal layer 1 DVD-ROM Digital versatile disks are read only. These disks are mechanically stamped and can be manufactured as single or double layer and as single sided or double sided. 2 DVD-R These are single or dual layer disks and can be single or double sided. They can be written to only once. 3 DVD-RW These are the same as DVD-R only that they can be written to several times. 4 DVD+R These are single or dual layer disks and can be single or double sided. They can be written to only once. 5 DVD+RW These are the same as DVD+R only that they can be written to several times. The screen size of a computer is measured diagonally in inches. The vary in size from 15 inch to 24 inch although the 19 inch in standard and widescreen is the most common with new computer systems. Another important measurement is the dot pitch. This is the distance between the pixels on the monitor and 0.24mm is considered adequate. Smaller dot pitches are available but at extra cost. The dot pitch controls the sharpness of the image. Most LCD monitors offer a VGA and a DVI connection to connect to the graphics card of the computer system. The VGA connector is used if a analogue signal is being sent from the graphics card and the DVI connector is used if the signal being sent is digital. Obviously, as the computer is a digital machine, it is best if no conversion is required and so the best option is the DVI connection. LCD monitors have a native resolution at which the image is crisp and clear. Other resolutions are possible but the image quality decreases. Keyboard The keyboard is the primary input device for the computer system. The board is divided into a number of sections: • Typing keys: This section contains the letter and number keys. The shift keys, spacebar, return key etc. are also included in this section. • Numeric keypad: These keys are arranged as on a calculator and are used in Banks etc. They allow numeric data to be entered much more quickly than using the numbers at the top of the typing keys. • Function keys: These are programmable keys used by software for special functions. E.g. - F1 is always used for help. • Control keys: The control keys are used for screen and cursor control. The arrow keys control the cursor. The Home, End, Page up etc. keys control cursor in software applications. DVI VGA The most common typing key arrangement is called QWERTY after the first six keys. Other typing key arrangements are available including Dvorak, ABCDEF, AZERTY etc. These are common in other countries but the qwerty keyboard has maintained dominance in Western Europe. Keyboards are available wired or wireless: • Wired: These are either PS/2 or USB. • Wireless: A wireless keyboard has two components. The keyboard and a receiver that connects to a USB port. The keyboard uses batteries. A full size rubber keyboard is useful for people who use notebook computers. Because the notebook keyboard leaves users more prone to RSI (Repetitive Strain Injury), a full size keyboard that rolls up to fit into a notebook carry case is an advantage. QWERTY Dvorak Wireless keyboard Mouse A mouse in an input device that uses point and click technology to interact with software applications. There are two main types: • Ball mouse: This uses a ball to roll across the surface and move rollers attached to sensors inside the mouse that reflect the ball movement as cursor movement. These are efficient devices but the ball picks up dust and looses friction with the rollers. As a result, the cursor movement becomes erratic. A mouse mat is needed to aid friction between the ball and the surface. • Optical mouse: This uses a camera to take thousands of images per second and sent them for digital processing. The red LED lights up the surface for the camera. The digital processor compares images and can sense the movement of the mouse. This movement is reflected on the screen as cursor movement. The great advantage of the optical mouse is that it is not effected by dust as a ball mouse is and a mouse mat is not required. It does not work well on glass surfaces. Both ball and optical mice are available as wireless. Batteries are required as for the wireless keyboard. Graphics tablets are becoming popular as a replacement for a mouse as they offer much more control of cursor movement. This is important in applications such as Illustration Graphics, Image Editing and CAD. Software designed for use with graphics tablets can sense the pressure applied to the stylus as well as the tilt angle etc. Ball mouse Optical mouse