Published on August 3, 2014
Types and components of Computer Systems: Types and components of Computer Systems By Rizwan Ahmad Introduction to the Computer: Introduction to the Computer The term computer is used for any device that may be employed to compute or to calculate. A computer is an electronic device that receives input, stores it for a period of time, operating it according to a set of instructions known as a ‘Program’ and gives the user with an output. -OR- Computer is an electronic device which converts data into information. A Computer is as intelligent as is the program that runs it. Without a program computer is useless. Computers cannot detect wrong feeding of data. Some of the features of a computer are Speed, Accuracy, Storage, Versatility, Automation and Diligence. Types of Computers: Types of Computers Computers come in all sorts of shapes and sizes. Based on Capacity, speed and reliability computers can be divided into the following categories of computers: PC/desktop computers usually refers to a general purpose computer which is made up of separate monitor, keyboard, mouse and processor unit. Laptop (or Notebook) refers to a type of computer where the monitor, keyboard, pointing device and processor are all together in one single unit. This makes them extremely portable systems. The key features of 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) . 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 screen and often a stylus to key in data. Netbooks don’t have optical drives. Personal digital assistants (PDAs) are small handheld computers that usually come with a touch screen that is activated using a stylus. Data is entered by using a keyboard that appears on the touch screen. PDAs now have basic database, word-processing and spreadsheet facilities. Mainframe computers is a term used for a large, very powerful computer system. Their main purpose is to run commercial applications such as banking and insurance, where huge amounts of data need to be processed each day. Main features: Multiple CPUs Fast processor speeds Multiple Operating Systems Huge RAM . Computer System: Computer System A computer system is the combination of hardware and software. A typical computer system has memory and set of states that define the relationship between the system's inputs and outputs. DATA- The collection of raw facts is called data. Without knowing the context (what the data actually represents) the data is just a meaningless collection of values. PROCESSING- The action required to be performed on data to convert it into result is called processing. RESULT- The useful information after processing of data is called result. INFORMATION- It is the collection of data according to a set parameter. With context, data is information. INPUT- The process of collecting and entering data into the computer is called input. OUTPUT- Output is the result we get after the processing of data and taking it out of memory. SYSTEM- A system is a group of interrelated components (Here Hardware and Software) that collectively achieve a desired result. Hardware, Software, Input and Output: Hardware, Software, Input and Output Hardware means the physical structure of a computer, i.e., the parts that can be touched by us. All the components attached to the computer like Keyboard, Mouse, Monitor, Printers are hardware. An correlation……. Your hardware is all of the parts that make up your body: bones, muscles, skin, blood, etc. Hardware is just a box with electronic parts in it. It cannot do any work by itself. It needs certain programs to do some work. Software is a general term used to describe a collection of instructions. These instructions tell the computer what to do. To continue the correlation…….. Your software is all of your thoughts and mental processes: these are the instructions that tell your physical body what to do. Hardware Components: We can categorize hardware components in three broad categories: Input Devices CPU, the Central Processing Unit, and Output Devices [Backing] Storage Devices or Secondary Memory. Input Unit: An input unit is a device through which data and programs from the outside world are entered into the computer Keyboard, the mouse, and scanning devices. Output Unit: An output unit is a device through which results stored in the computer memory are made available to the outside world Printers and video display terminals. PowerPoint Presentation: Central Processing Unit CPU stands for Central Processing Unit. It is a small chip inside the computer. It does all decisions, calculations. It also controls other parts of a computer. CPU consists of several section: Control Unit (CU) Arithmetic and Logic Unit (ALU) Main Memory Each of the section has its own function. They work together with other Peripherals to form a computer. 1. Control Unit Control Unit controls operations of other parts of CPU as well as all parts of computer by sending a control signal, e.g. control sequence of instruction to be executed control flow of data among all parts of computer interpret instructions regulate timing of processor send control single to and receive control single from peripheral devices The control unit of the CPU contains circuitry that uses electrical signals to direct the entire computer system to carry out, or execute, stored program instructions. Like an orchestra leader, the control unit does not execute program instructions; rather, it directs other parts of the system to do so. The control unit must communicate with both the arithmetic/logic unit and memory. 2. Arithmetic and Logic Unit Arithmetic and Logic Unit consists of a complicated set of logic circuit and accumulator. It is mainly responsible for Calculation Logical comparison and decision. 3. Main Memory is a collection of cells, each with a unique physical address The size of a cell is normally a power of 2, typically a byte. A cell is the smallest addressable unit of memory – i.e. one cell can be read from memory or one cell can be written into memory, but nothing smaller. Each cell has an address, starting at 0 and increasing by 1 for each cell. A cell with a low address is just as accessible as one with a high address- hence the name RAM. The width of the cell determines how many bits can be read or written in one machine operation. PowerPoint Presentation: The main memory holds the program instructions and data. It contains two types of memory chip, called ROM and RAM. Random Access Memory (RAM) is the part of the computer that temporarily stores the instructions that the computer is running, and the data it is processing. RAM is a volatile storage device. When a computer is in use, its RAM will contain… The operating system software The application software currently being used Any data that is being processed. Read-Only Memory (ROM) is used in most computers to hold a small, special piece of software: the 'boot up' program. This software runs when the computer is switched on or 'boots up'. The software checks the computer’s hardware and then loads the operating system. RAM is volatile, ROM is not: This means that RAM does not retain its bit configuration when the power is turned off, but ROM does. Storage Devices Secondary or backing storage is used to store programs and data when they are not being used i.e. used to store permanently. Secondary storage is non-volatile, so data that is stored on these devices remains there safely. A hard drive, a CD-ROM, a floppy disc and a USB memory stick are all examples of secondary storage devices. Magnetic Tape The first truly mass auxiliary storage device was the magnetic tape drive. Magnetic Disks A read/write head travels across a spinning magnetic disk, retrieving or recording data. Compact Disks A CD drive uses a laser to read information stored optically on a plastic disk CD-ROM is Read-Only Memory DVD stands for Digital Versatile Disk. Peripheral Devices Peripheral devices are not part of the central core of the computer. The general name for extra/additional devices is ‘peripheral devices’. They are usually categorized into input devices, output devices and storage devices. CD-ROM drive, Mouse, Printer, Speaker, Scanner, Zip drive are some examples of peripheral devices. The Difference Between Hardware and Software: The Difference Between Hardware and Software Hardware Computer hardware is the physical components that make up the computer system. Hardware is useless without software to run on it. Software is instructions that tell computer hardware what to do. Software is useless unless there is hardware to run it on. Software For a computer system to be useful it has to consist of both hardware and software. Hardware is the actual components that your computer is made of: ram, rom, motherboard, modem, wireless chip etc. Software is any program that you load onto a computer: the operating system (Windows, Linux) games or applications. Completing the correlation………… Your physical body cannot function without your thoughts. And your thoughts need a physical body to exist within. PowerPoint Presentation: Types of Software : System Software A system software package is a collection of programs designed to operate, control, and extend processing capabilities of computers. Operating System is one of the system software. Application Software An application software is a set of programs that allow computer to perform a specific data-processing job for the user. Special Purpose Software General Purpose Software. Utility Software Utility software is special purpose software that improves the operations of system software by providing additional and specialized functionality to it. It helps to keep your system in shape by eliminating/correcting error. Utility is a program that performs a very specific task, usually related to managing system resources. Operating Systems : An Operating System is the most important program that runs on a computer. Every general-purpose computer must have an operating system to run other programs. Operating systems perform basic tasks, such as recognizing input from the keyboard, sending output to the display screen, keeping track of files and directories on the disk, and controlling peripheral devices such as disk drives and printers. Operating systems provide a software platform on top of which other programs, called application programs, can run. The application programs must be written to run on top of a particular operating system. Your choice of operating system, therefore, determines to a great extent the applications you can run. The platform defines a standard around which a system can be developed. The operating system controls problems In any computer, the operating system: controls the backing store and peripherals such as scanners and printers deals with the transfer of programs in and out of memory organizes the use of memory between programs organizes processing time between programs and users maintains security and access rights of users deals with errors and user instructions allows the user to save files to a backing store. The platform defines a standard around which a system can be developed. PowerPoint Presentation: User Interfaces: A user interface is the method by which the user and the computer exchange information and instructions. There are two main types: Command Line or Character User Interface (CUI) Graphical User Interface (GUI). User Interfaces Command-line interfaces A command-line interface allows the user to interact with the computer by typing in commands-set of instruction. The computer displays a prompt, the user keys in the command and presses enter or return. An example of a common command driven interface is MS-DOS. Features of a command-line interface Commands must be typed correctly and in the right order or the command will not work. Experienced users who know the commands can work very quickly without having to find their way around menus. An inexperienced user can sometimes find a command driven program difficult to use because of the number of commands that have to be learnt. User Interfaces Graphical user interfaces Graphical user interface is sometimes shortened to GUI. The user chooses an option usually by pointing a mouse at an icon representing that option. Features of GUIs include: They are much easier to use for beginners. They enable you to easily exchange information between software using cut and paste or 'drag and drop'. They use a lot of memory and processing power. PowerPoint Presentation: User Interfaces When discussing user interfaces, it is important to note that Windows XP, Windows Vista, Apple OSX and Ubuntu all have graphical user interfaces. Windows XP: an operating system by Microsoft Windows 7: an operating system by Microsoft Windows Vista: an operating system by Microsoft Apple OSX: an operating system by Apple Computers Ubuntu: an open source (freely available) operating system Simply, a GUI is a one where the Operating System uses a WIMP- Windows Icons Menus Pointers environment. Points to Remember The speed of a CPU is measured in Hertz (Hz). The speed generally corresponds to the number of actions the CPU can perform every second.1 Megahertz (MHz) is 1,000,000 (1 million) Hertz 1 Gigahertz (GHz) is 1,000,000,000 (1 billion) Hertz A typical, modern, fast CPU runs at around 2.8GHz. That means it can perform almost 3 billion actions every second!