TYPES AND COMPONENTS OF COMPUTER SYSTEMS, Study notes of Operating Systems

Download TYPES AND COMPONENTS OF COMPUTER SYSTEMS and more Study notes Operating Systems in PDF only on Docsity! vinodsrivastava.wordpress.com SECTION 1 TYPES AND COMPONENTS OF COMPUTER SYSTEMS Hardware and Software Computer hardware is the collection of physical elements that constitute a computer system. Computer hardware refers to the physical parts or components of a computer such as monitor, keyboard, Computer data storage, hard drive disk, mouse, system unit (graphic cards, sound cards, memory, motherboard and chips), etc. all of which are physical objects that you can actually touch. Computer Hardware are broadly divided into four types  Input Devices : Hardware used to input data into computer system like keyboard, mouse  Output Devices Hardware used to output processed data from computer system like Monitor, printer  Storage Devices Hardware used to store the data like hard disk ,Pen, Drive, CD  System Unit: Hardware present in System Unit Like CPU , Motherboard, Graphics Card, Data Bus, System Cables, Ports etc This Section you will learn about:  HARDWARE  SOFTWARE  THE MAIN COMPONENTS OF A COMPUTER SYSTEM  OPERATING SYSTEMS: o GRAPHICAL USER INTERFACE (GUI) o COMMAND LINE INTERFACE (CLI)  DIFFERENT TYPES OF COMPUTER SYSTEMS. SECTION 1: TYPES AND COMPONENTS OF COMPUTER SYSTEMS IGCSE ICT-0417@ VKS-Learning Hub Page 2 Label the hardware given below 1._____________________________________ 2._____________________________________ 3._____________________________________ 4._____________________________________ 5._____________________________________ 6._____________________________________ 7._____________________________________ 8._____________________________________ 9._____________________________________ 10.____________________________________ Computer software is a set of programs, procedures, code and related data that provide the instructions for telling computer hardware what to do and how to do it Software are broadly divided into two types  System Software: System software is any computer software which manages and controls computer hardware so that application software can perform a task. Operating systems, such as Microsoft Windows, Mac OS X or Linux, are prominent examples of system software  Application Software application software are programs that enable the end-user to perform specific, productive tasks, such as MS Word for word processing or Photoshop for image manipulation. Hardware and Software have a symbiotic relationship, this means that without software hardware is very limited; and without hardware, software wouldn't be able to run at all. They need each other to fulfill their potential. SECTION 1: TYPES AND COMPONENTS OF COMPUTER SYSTEMS IGCSE ICT-0417@ VKS-Learning Hub Page 5 The motherboard is the main circuit board of the system unit PROCESSOR (CPU) The central processing unit (CPU) is the part of the computer which interprets and executes the commands from the computer hardware and software. CPUs used to be made up of discrete components and numerous small integrated circuits, which were combined together on one or more circuit board/s. However, due to modern manufacturing techniques, the term microprocessor is now used instead of CPU. This is a single integrated circuit (see Figure 1.2) 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 (e.g. the engine management system in a car). CPU or Processor have Two Parts 1 Arithmetic Logical Unit(ALU): The arithmetic logic unit (ALU) performs arithmetic, comparison and other operations. 2. Control Unit: The control unit is the component of the processor that directs and coordinates most of the operations in the computer operations SECTION 1: TYPES AND COMPONENTS OF COMPUTER SYSTEMS IGCSE ICT-0417@ VKS-Learning Hub Page 6 Flow of CPU Working For every instruction, a processor repeats a set of four basic operations, which comprise a machine cycle The processor contains registers, that temporarily hold data and instructions The system clock controls the timing of all computer operations.The pace of the system clock is called the clock speed, and is measured in gigahertz (GHz) SECTION 1: TYPES AND COMPONENTS OF COMPUTER SYSTEMS IGCSE ICT-0417@ VKS-Learning Hub Page 7 Memory Memory consists of electronic components that store instructions waiting to be executed by the processor, data needed by those instructions, and the results of processing the data. Stores three basic categories of items:  The operating system and other system software  Application programs  Data being processed and the resulting information Memory size is measured in kilobytes (KB or K), megabytes (MB), gigabytes (GB), or terabytes (TB) The internal hard drive is the computer’s main memory; this is where the applications software, disk operating system and data files are stored. The main advantage of these memories is the fast data transfer/access times and their large capacity to store data (this is discussed further in Chapter 3). Main/Internal memory (including ROM and RAM) This is the type of memory that can be read from and written to by the processor and other devices. Programs and data are loaded into RAM from storage devices such as a hard disk and remain in the RAM as long as the computer has continuous power. The system unit contains two types of 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. Since its contents are lost when power to the computer is turned off, it is often referred to as a ‘volatile’ or ‘temporary’ memory. RAM chips usually reside on a memory module and are inserted into memory slots There are Two Basic types of RAM chips exist: • Static RAM (SRAM) : SRAM retains its contents as long as the power is connected and is easy to interface to but uses six transistors per bit. • Dynamic RAM (DRAM) Dynamic RAM is more complicated to interface to and control and needs regular refresh cycles to prevent its contents being lost. However, DRAM uses only one transistor and a capacitor per bit. SECTION 1: TYPES AND COMPONENTS OF COMPUTER SYSTEMS IGCSE ICT-0417@ VKS-Learning Hub Page 10 Utility Program is a type of system software that allows a user to perform maintenance-type tasks. Examples of Utility Programs : Windows Explorer (File/Folder Management), Compression Tool, Anti-Virus Utilities, Disk Defragmentation, Disk Clean, BackUp, WinZip, WinRAR etc… USER INTERFACE A user interface controls how you enter data and instructions and how information is displayed on the screen There Are Two User interface provided by Operating System Graphical User Interface (GUI): User interact the system through WIMP environment- Windows, Icon, Menus, and Pointers (WIMP). GUIs are small pictures that represent actions, and they can be selected by ‘clicking’ on them with the mouse. Example of GUI interface Windows & Mac OS Command line interfaces(CLI) CLIs require a user to type in instructions in order 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 therefore 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 CLI is that the user is in direct communication with the computer and is not restricted to a number of pre-determined options. Example DOS SECTION 1: TYPES AND COMPONENTS OF COMPUTER SYSTEMS IGCSE ICT-0417@ VKS-Learning Hub Page 11 Types of computers There are many types of computer systems in existence. This section summarizes some of the more common types currently available. PC/desktop computers PC/desktop usually refers to a general purpose computer which is made up of separate monitor, keyboard, mouse and processor unit (see Figure 1.1). The term PC (personal computer) usually refers to computer systems which are IBM- compatible, thus distinguishing them from, for example, Macintosh systems. Advantages ● Spare parts and connections tend to be standardised, which usually results in low costs. ● Desktops tend to have a better specification (e.g. faster processor) for a given price(often due to size and construction constraints in laptops). ● The large casing allows good dissipation of any heat build-up. Disadvantages ● Desktops are not particularly portable since they are made up of separate components. ● All the components need to be hooked up by wiring, which can be quite complex and clutters up the desk space. ● Because they are not particularly portable, it is necessary to copy files, etc. when you want to do some work elsewhere (e.g. at home). Laptop computers Laptop (or notebook) refers to a type of computer where the monitor, keyboard, pointing device and processor are all together in one single unit. The key features you would expect to find in a laptop are: ● low weight (to aid portability) ● low power consumption (and also long battery life) ● a processor that does not generate too much heat (cooling is very important). Advantages ● They are very portable, since the monitor, pointing device, keyboard, processor and backing store units are all together in one single box. ● There are no trailing wires, etc. because everything is in one single unit. ● They can take full advantage of WiFi (see discussion in Chapter 4). ● Since they are portable, they can link into any multimedia system. SECTION 1: TYPES AND COMPONENTS OF COMPUTER SYSTEMS IGCSE ICT-0417@ VKS-Learning Hub Page 12 Disadvantages ● Since they are portable, they are easy to steal! ● They have limited battery life so the user may need to carry a heavy adaptor. ● The keyboards and pointing devices can sometimes be awkward to use. ● Heat dissipation is more difficult due to the structure of the laptop computers. Netbooks Netbook is a term used to describe a computer that can almost fit onto a hand and is a smaller version of a laptop. These used to be known as palmtop computers, but this term now generally applies to much smaller devices which use touch screens and often a stylus to key in data (see below). Advantages Netbook computers have many of the features of laptops and therefore have similar advantages and disadvantages. Disadvantages In addition to the disadvantages listed above for laptops: ● netbooks don’t have optical drives ● the keyboards are only about 80 per cent the size of laptop keyboards ● they lack some of the features found in larger machines, principally due to the size constraints and to the fact that they are cheaper to purchase. Personal digital assistants Personal digital assistants (PDAs) are small handheld computers that usually come with a touch screen that is activated using a stylus. Data (e.g. text) is entered by using a keyboard that appears on the touch screen. Originally, these devices were used as personal organisers but their use has expanded somewhat to include new generation mobile phones, data loggers, satellite navigation systems, etc. Many PDAs now have basic database, word-processing and spreadsheet facilities. Advantages ● They can be used anywhere because of their size. ● They are very lightweight and are more portable than laptop computers. Disadvantages ● It is difficult to enter text quickly. ● They have very limited capabilities due to the software and the operating system used.