Types and components of computer systems chapter you will learn about: hardware software analogue and digital data central processing unit [CPU] internal memory (RAM and ROM) input and output devices backing store operating systems types of computer - desktop computers and mobile computers (laptop, smartphone, tablet and phablet} emerging technologies - artificial intelligence (Al) and extended reality virtual and augmented). een aerate Se tee ee ee een ce ee ee eee Re ee Cet ee eee a eee oa Ce amet and internal) and software (both applications and system, are all briefly introduced in the following sections. UL ee Cee EEUU) and the ink used on the pages are equivalent to the hardware used to make up computers; the words written on these pages are equivalent to the software. Without the words, the book is useless. Similarly, without software, computers would be of little use to any of us. 1.1 Hardware and software 1.1.1 Hardware Hardware is the general term for the physical components that make up a typical computer system. For example: keyboard » mouse | input device » monitor »> printer |i device » plotter Hardware falls into two categories: internal and external. The list above are examples of external hardware, which is discussed in detail in Chapter 2. Figure 1.1 considers the following internal hardware devices: » motherboard » central processing unit (CPU)/processor » random access memory (RAM) ¥1L1 Hardware and software » read-only memory (ROM) » graphics card » sound card » network interface card (NIC) » internal storage devices (hard disk drive and solid-state drive). Because it is not always possible to see the internal hardware devices, the photographs in Figure 1.2 will give you some idea of the physical appearance of the components described in Figure 1.1. 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Figure 1.1 Internal computer hardware‘TYPES AND COMPONENTS OF COMPUTER SYSTEMS Motherboard: = Sound cards sso: > oD: ‘A. Figure 1.2 Examples of internal hardware 1.1.2 Software Software is the general term used for the programs that control the computer system and process data. The software considered in this book falls into two categories: applications and system. Applications software provides the services that the user requires to solve @ given task. For example: word processing spreadsheet database (management system) control and measurement software apps and applets video editin: graphics editing audio editing computer-aided design (CAD). veyeryeey (Refer to Figure 1.3 for more details.) System software is the software designed to provide a platform on which all other software can run. For example: » compilers » linkers » device drivers »> operating systems » utilities. (Refer to Figure 1.4 for more details.)1L1 Hardware and software Word processing Spreadsheet Database (management system) Word processing software is used to Spreadshest software is used to organise Database software used to organise, manipulate text document, such as an ‘and maniuiaterumerial data in the ‘manipulate and analyse data. A typical essay or report. Tet i entered using a form of intoger, real, date, and soon). database is made up of one or more beyboard and the software provdes took: Numbers ate organised on aan of tables. Tadles Cons of rows and {ot copying, deleting and various types eter columns and numbered rons. The columns. Each row is called a recor ‘of formating. Some ofthe functions ot id iself s made up of cel, and each cel ‘and each column & called a field’ This word processing software include ' denied using a unique comtination of [provides the base structure forthe * creating, editing, saving and ‘coluims and rows for example: 86, Some ‘organisation of the data within the: manipulating text ‘ofthe functons of spreadsheets incude: database. Some ofthe functions include: copy and paste functions use of formule to cary out ‘ abily ta cary out queries on database + spall checkers and thesaurus calculations Gata and produce a report (08M) ‘import photos/mages into a structured + ablity to produce graphs ‘add, delete and modty data in a table. page format + ably to do modeling and what i transition into foreign language, ‘alaulations, ‘Apps and applets ‘Applets are small applications that perform a single task on a device (they ‘fe usually embedded in an HTML page (on a website and can be executed from within a browse, ‘Apps refer to software which can perform a fay substantial ask (such Control and measurement software 2 video and music streaming, banking Control and measuring software is ‘pplication or social media). The term designed to allow a computer or originally referred to software that ran microprocessor to interface with sensors (on 2 smartphone and could be 50 that itis possible to: downloade from an ‘app store’. ‘+ measure physical quantities in the real APPLICATIONS SOFTWARE + onto opps Guha tte do ects Computer ated design (CAD) ‘chemical process) by comparing sensor shan data with stored data and sending out Thisis software used to help in the signals to alter process parameters (or cee eet ec ‘example, open a valve to add acid and and analysis of a drawingdesian. damteah Hcan be used to produce 2D or 30 diagrams which + canbe rotated to view the drawing {rom any angle + can produce full cimensions © canbe used tocestimate ‘manufacturing cost ofthe final product + predict any structural problems Audio editing software Video eaiting software Graphics editing software ‘Audio editing software allows a user to Video editing software allows 2 user the Graphics eaiting software allows bitmap edit, manipulate and generate audio data bility to manipulate videos to produce and vector images to be changed. ‘ona computer It alows the user to alter ‘2 NeW vdeo. It enables the addtion of Bitmap images are made up of pines ‘length of tack tiles, colour conection and aterng/ ‘which contain information about image «= starstop time of track ‘adding sound tothe onigna video, brightness and colour. Bitmap graphics + convarson between au file formats Fenty it ince: ‘editors can change the pels to produce + Volume of track + rearanging, adaing and/or removing ‘different image. Vector graphic editors ‘fading infout Sections of video clips andor audio operat in a different way and do not use} + combine multiple sound tracks ips hel. This ype of software manipulates “= noise reduction + applying colour correction, fiers and lines, curves and tax to alter the stored “to ceate another version of the sound other video enhancements image as required. Bath types of eating ‘tack for example, a continuous loop «creating transitions between clips in sofware are chosen depending on the ‘or phone ring tone). the video footage. ‘format of the orginal image ‘A. Figure 1.3 Applications software1 ‘TYPES AND COMPONENTS OF COMPUTER SYSTEMS Linkers Deve river ‘Acompleris a computer program that Anke (or link editor 3 computer [Addeves drivers the name given 9 trartes a program wntten ma program that fakes one of more object Software that enabies one o more higheve language (HLL) to machine ier produced by 2 compler and ardware devices tocommuneate with code (Code that undest0od by the combines them nto a sng program the computer's operating system computer) 20 tat tean be drecty that can be run on @ computer For \Wehour vere, @Rerdwere device (or used by a compute to perform a Jexampie, many programming example, 2 printer) would be unable to requred tax The original program is languages allow programmers 1 Work with the computer. Al hardware {led the source code and the code write diferent peces of code, called eves comecte fo a computer have ‘her compiston iealed the object ‘Modules separtely Tae arms fe=sme Ssrocated arvers Ax soon ara deuce © ‘code. Once a program s compiled, programming task snce it alow the plugged no the USB port ct a ‘he machine code can be used 258% program to Be broken tp ita mal, Eomputer he operating stem looks for ‘and again to perform the same task fore manageable sub tasks, However, the appropite ver. An eor message “thea recompiston Samples of [sis pare tol ae neseesyso willbe produced ft cannot be found higheve languoges induce Java, puta the modules together to form Examples of herdivere davies at Python, Vieuel Bane, Ferran, Coe {She nl program The she so ot requre drivers include panters, memory and Algal she lnk. sick, mouse, CD drves, and 0 on Operating systems (05) utilities The operatng ster (05) esertily Unity programe are sofware that has software running inthe background of been desged to cry out spent acomp.tersjsiem ftmanages many ‘asks on a computer Essential, they ofthe base functions. Without the 05, sre progioms hat hep to manage, ee ranean and cone) computer Useruntendly andthe ma resourees. Examples include: lsers would find almost impossible SSEM SOW aae saa towork with computersona ae ee oe eo |. pacar foun propery tack es eae ‘communcate with disk rep * mputfoutput operations ‘ile management Ges to communicate th the cocoate meurty computer for example, Windows) 2 sceensovers 0% handing 1 ake place + Geecehagmenter “he casing and unnng ot programs to occur ‘+ managing of securty (for example. ‘se accounts, log on passwords “Figure 1.4 System software 1 -1.3 Analogue and digital data Computers can only understand data which is in a binary format (that is, a base 2 number system where only the values 0 and 1 can be used). This is often referred to as digital data (because it can only have discrete, discontinuous values). However, data in the real world is actually analogue in nature. Analogue data is physical data that changes smoothly from one value to the next, and not in discrete steps as with digital data, 5 5 4 2 2 1 ° a Figure 1.5 Analogue and digital data1.2 Main components of computer systems In Figure 1.5, the graph on the left shows analogue data; an infinite number of values can exist between 0 and 6 (for example, 2.5, 4.652, and so on) because the curve is smooth in shape. The graph on the right shows digital data; notice only the exact values of 0, 1, 2, 3, 4, 5 or 6 can be taken. If analogue data is being sent to a computer, it must first be converted into digital data; this is done by hardware known as an analogue to digital converter (ADC). If the computer is controlling a device (such as a motor) then the digital output from the computer needs to be converted into analogue form. This is done by a digital to analogue converter (DAC). 1.2 Main components of computer systems As already mentioned in Section 1.1, a typical computer system is made up of hardware and software. The diagram in Figure 1.6 shows an example of a computer system consisting of input devices, output devices and secondary storage. These will be discussed in more detail in Chapter 2, but some examples are listed in Table 1.1. ¥ Table 1.1 Examples of input, output and secondary storage devices Device Examples Input devices keyboard, mouse, camera, microphone, sensor, scanner Output devices ‘monitor, printer, speakers, projector, (graph! plotter Secondary storage devices hard disk drive, solid-state drive, pen drive The internal hardware devices were shown in Figure 1.2 - these consist of four key components: » the central processing unit (CPU) (contained on the motherboard) » internal hard disk drive or solid-state drive » random access memory (RAM) » read-only memory (ROM). mroprocesorand internal memory and storage devices computer printer keybonrs A. Figure 1.6 A typical computer system‘TYPES AND COMPONENTS OF COMPUTER SYSTEMS 1.2.1 CPU The central processing unit (CPU) is the part of the computer that interprets and executes the commands from the computer hardware and software. It is normally part of the computer motherboard. CPUs used to be made up of discrete components and numerous small integrated circuits; these were combined together on one or more circuit board(s). However, due to modem manufacturing techniques, the CPU is now referred to as a microprocessor. This is a single integrated circuit which is at the heart of most PCs and is also found in many household devices and equipment where some control or monitoring is needed (for example, the engine management system in a car). The CPU/microprocessor is made up of a control unit, which controls the input and output devices; an arithmetic and logic unit (ALU), which carries out calculations and makes logical decisions, and small memory locations called registers. 1.2.2 Internal memory Random access memory (RAM) is an internal chip where data is temporarily stored when running applications. This memory can be written to and read from. Because its contents are lost when power to the computer is turned off, it is often referred to as a volatile or temporary memory. This was fully described in Figure 1.1. Read-only memory (ROM) is a memory used to store information that needs to be permanent. It is often used to contain, for example, configuration data for a computer system. Chips used for ROM cannot be altered and can only be read from (hence their name). One of the main advantages is that the information stored on the ROM chip is not lost, even when power is turned off to the computer. They are often referred to as non-volatile memories. This was fully described in Figure 1.1. It is worth noting that that ROM also contains some coding known as the boot file. This code tells the computer what to do when it first starts up; it is often referred to as the BIOS (basic input/output system). When the computer is turned on, the BIOS carries out a hardware check to find out if all the devices are present and whether they are functional. Then it loads the operating system into the RAM. The BIOS stores the date, time and system configuration in a non-volatile chip called a CMOS (complementary metal oxide semiconductor) ~ this is usually battery powered. Table 1.2 provides a summary of the main differences between RAM and ROM. ¥ Table 1.2 RAM and ROM differences RAM ROM ‘Temporary memory device Permanent memory device Volatile memory Non-volatile memory device Can be written to and read from Read-only, data stored cannot be altered Used to store data, files, programs, part of ‘operating systems {0S} currentiy in use Used to store BIOS and other data needed at Can be increased in size to improve start up operational speed of a computer1.2 Main components of computer systems 1.2.3 Input and output devices Input devices are hardware that allows data to be entered into a computer (these are covered in detail in Chapter 2). They use either manual entry (such as a keyboard or a mouse) or direct data entry (such as sensors or optical character readers). Essentially, these devices turn input into a form the computer can understand - for example, a mouse turns hand movements into cursor movements on the screen. As mentioned earlier, sometimes the data has to go through an ADC before the computer can make any sense of it. When a computer processes data, and the human operator wants to see the results of the processing, then the computer sends the data to an output device. ‘An output device shows the computer's output in a form that is understood by a human ~ for example, as text on a printer or moving images on a monitor. Some devices can act as both input and output. For example, a touch screen can do both, as can a DVD writer/player; but most devices are only capable of either ‘inputting data into a computer or displaying the results of computer processing (output device). Table 1.3 summarises the differences between input and output devices. ¥ Table 1.3 Comparison of input and output devices Input devices ‘Output devices An output device is any hardware device that takes the output data from a computer and puts into @ human-readable format or uses itto control another device. ‘An input device is any hardware device that allows a user to enter data or instructions into a computer directly ‘An output device is capable of receiving data ‘An input device can send data to another device, but it cannot receive data from another device, from another device in order to generate an output, but it cannot send data to another device. Input devices are necessary for a computer to receive commands from its users and data Output devices are needed by a computer so it can share the results ofits pracessing witha human; output devices are under the control of the computer. to process; the devices are under the control ‘of the user or can be direct data entry. Input devices can be fairly complicated because they have to ensure that the user ‘can interact with the computer correctly Output devices are less complex than input devices because they only have to turn computer signals into an output 1.2.4 Backing storage The main memories in a computer are RAM and ROM. However, to permanently store large amounts of data it is necessary to use backing storage. This normally takes the form of the internal hard disk drive (HDD) or solid-state drive (SSD). This is the computer's main internal storage where the applications software, disk operating system and files (for example, text, photo or music) are stored. A key feature of a backing store is that it must store data permanently - that is, it must be non-volatile. Unlike RAM and ROM, backing storage is not directly addressable (that is, it cannot be read directly by the CPU). The data access time for RAM and ROM is much shorter than it is for backing storage. Backing storage is considerably larger ‘than RAM because it is considerably less expensive per byte.‘TYPES AND COMPONENTS OF COMPUTER SYSTEMS Backing storage can either be fixed (very often internal to the computer) or removable. The advantage of removable backing storage is that it can be used as a backup in case of data loss or corruption. Data from the main HDD or SSD can be copied onto another device (such as a pen drive or portable HDD) and then stored in a separate location. If the original data on the HDD/SSD has been lost or corrupted, it can be restored from the backup device. Examples of removable storage include external hard disk drives (HDD), external solid-state drive (SSD) and Blu-ray discs. Table 1.4 summarises the differences between backing storage and internal memory. ¥ Table 1.4 Comparison of internal memory and backing storage Internal memory Backing storage RAM contents are lost when computer is powered down; ROM contents are readable Backing storage devices hold their contents permanently, even when powered down, only. RAM and ROM are much smaller memories | Have considerably larger capacity to store than backing storage, data than RAM or ROM. Data access time on RAM and ROM is Has much slower data access time than extremely fast. RAM and ROM, Much more expensive per byte than backing eee oe Is much cheaper per byte than RAM or ROM. RAM and ROM are fixed inside the computer | Backing storage can either be fixed linternat memories) (external or internal) or it can be removable. Before data on a backing storage device can RAM and ROM can be readdirctly bythe | be read by the CPU, it must first be moved cpu. into RAM; this means backing storage is not directly addressable by the CPU. 1.3 Operating systems Reference to operating systems has already been made earlier on in this chapter (see Figure 1.4). To enable computer systems to function and to allow users to communicate with computer systems, special software, known as operating systems (0S), have been developed. The general tasks for a typical operating system include: control of the operation of the input, output and backing storage devices supervising the loading, running and storage of applications programs dealing with errors that occur in application programs maintaining security of the whole computer system maintaining a computer log (which details computer usage) allowing communication between user and the computer system (user interface). vUyEey1.3 Operating systems 1.3.1 User interfaces Operating systems offer various types of user interface. We will consider four different types: » command line interface (CLI) » graphical user interface (GUI) » dialogue-based user interface » gesture-based user interface. Command line interface (CLI) A command line interface (CLI) requires a user to type in instructions to choose options from menus, open software, etc. There are often a number of commands that need to be typed in, for example, to save or load a file. The user has to learn ‘a number of commands just to carry out basic operations. It is also slow, having to key in these commands every time an operation has to be carried out. However, the advantage of a CLI is that the user is in direct communication with the computer and is not restricted to a number of pre-determined options. For example, Windows has a CLI called the ‘command prompt’. The following command opens the desktop folder in Windows Explorer: wvindir%\explorer.exe C:\Users\YourName\Desktop -& Figure 1.7 Sample of CLI code The statements in Figure 1.7 show how complex it is just to carry out a fairly straightforward operation using CLI Graphical user interface (GUI) A graphical user interface (GUI) allows the user to interact with a computer (or MP3 player, gaming device, mobile phone, etc.) using pictures or symbols (icons) rather than having to type in a number of commands. For example, the whole of the CLI code in Figure 1.7 could have been replaced by clicking on the Desktop icon within Windows Explorer. Simply selecting this icon would automatically execute all the commands shown in Figure 1.7 without the need to type it in. GUIs use various technologies and devices to provide the user interface. One of the most common is WIMP (windows icons menu and pointing device) which was developed for use on personal computers (PC). Here, a mouse is used to control a cursor and icons are selected to open/run windows. Each window‘TYPES AND COMPONENTS OF COMPUTER SYSTEMS ‘Figure 1.8 Screen image showing icons contains an application and modern computer systems allow several windows to be open at the same time. An example is shown in Figure 1.8 (here, a number of ‘cons can be seen on the on the bottom of the screen ‘window’): ‘A window manager looks after the interaction between windows, the applications and window system (which handles the pointing devices and the cursor’s position). In recent years, devices such as touch screen smartphones and tablets use post- WIMP interaction, where fingers are in contact with the screen allowing actions such as pinching and rotating, which would be difficult to do using a single pointer and device such as a mouse. Table 1.5 summarises the main advantages and disadvantages of CLI and GUI. Y Table 1.5 Advantages and disadvantages of CLI and GUI interfaces Interface | Advantages Disadvantages The useris in direct communication with the computer. Command line interface (CLI) The users not restricted to a ‘number of pre-determined options. Itis possible to alter computer, configuration settings, |The user does not need to learn any commands tis more user-friendly: icons are Graphical | used to represent applications. user interface foun A pointing device (such as a mouse) is used to click on an icon to Launch the application - this is simpler than typing in commands. The user needs to learn a number of commands to carry out basic operations. All commands need to be typed in, which takes time and can be error~ prone, Each command must be typed in using the correct format, spelling, and so on. This type of interface uses up considerably more computer memory than a CLI interface. The user is limited to the icons provided on the screen, Needs a more complex operating system, such as Windows, to operate, which can be slower to execute commands,1.3 Operating systems Who would use each type of interface? CLI: a programmer, analyst or technician; basically, somebody who needs to have direct communication with 2 computer to develop new software, locate errors and remove them, initiate memory dumps (contents of the computer memory at some moment in time), and so on. GUI: the end-user who does not have to (or does not need to) have any great knowledge of how the computer works; @ person who uses the computer to run software, play games or store/manipulate photographs, for example. Dialogue-based user interfaces Dialogue-based user interfaces use the human voice to give commands to a computer system, An example of its use is in some luxury modern cars, where voice activation is used to control devices such as the in-car entertainment system or satellite navigation system. By speaking certain commends, such as ‘Hey BMW, drive me to the nearest airport, the system allows natural speech to enable the driver to intuitively interact with the car. The satellite navigation system will automatically direct the driver to their chosen destination (in this case, the nearest airport). This type of interface could also be used in the home; by using voice commands, it is possible to switch on/off lights, operate electronic equipment and so on. In recent years, devices such as Amazon Alexa, Google Now, Apple Siri and Microsoft Cortana have all been developed to interact with a human by recognising verbal commands. These devices act as a personal assistant. 41:48 trom Terminal 1 ‘Would you tke me to 10 Paphos? make you a booking? smart device is Human voice is Smart device processes asked question Converted into the human command and byanuman binary stream outputs a verbal response A. Figure 1.9 Smart voice activated devices Gesture-based interfaces Gesture-based interfaces rely on human interaction by the moving of hands, head or even the feet. Gesture recognition allows humans to interface with a computer in a more natural fashion without the need for any mechanical devices. This type of interface uses techniques known as computer vision and image processing. For example, using our car example again, the following gestures can be used to carry out certain functions: » rotating a finger clockwise near the radio will increase the sound volume (rotating the finger anti-clockwise will reduce the sound volume)