Computer System PDF

COMPUTER SYSTEM  COMPUTER SYSTEM Definition: Is a collection of entities( hardware, software and liveware ) that are designed to receive, process, manage and present information in a meaningful format.  COMPONENTS OF COMPUTER SYSTEM The computer has mainly has two major compon...

COMPUTER SYSTEM  COMPUTER SYSTEM Definition: Is a collection of entities( hardware, software and liveware ) that are designed to receive, process, manage and present information in a meaningful format.  COMPONENTS OF COMPUTER SYSTEM The computer has mainly has two major components: 1. Hardware 2. Software Computer hardware is a physical device of computers that we can see and touch. For e.g. Monitor, Central Processing Unit, Mouse, Joystick, etc. Using these devices, we can control computer operations like input and output.  Computer Hardware Parts These hardware components are further divided into the following categories, which are: 1. Input Devices 2. Output Devices 3. Storage Devices 4. Internal Components  1. Input Devices Input devices are those devices with the help of which the user interacts with the computer. Or, In other words, with the help of input devices, the user enters the data or information into the computer. Some input devices: Keyboard: It is the most common and main input device for computers. The data is inputted by typing on the keyboard. It consists of 104 keys in total. It contains numeric keys, alphabet keys, and different function keys as well. Earlier, it was connected to the computer via cable, now as technology has advanced, you can connect a keyboard using Bluetooth.  1. Input Devices Mouse: A mouse is a kind of pointing device which is rolled over to control the cursor on the screen and it has functional keys like left, middle, and right buttons. Using these functional keys, on by the click of which an object is selected or to open a file by just a click of a mouse. It also consists of a sensor inside which notifies its speed to the computer and according to which the cursor is moved on the screen.  1. Input Devices Scanner: As the name suggests, it scans images, documents, etc., and converts them into digital form and that can be further edited and used. It works just like a Xerox machine. Track Ball: It is a device much like an upside-down mouse. It does not use much space for movement like a mouse. As the trackball remains stationary and the user moves the ball in various directions, it affects the screen movements directly. Light Pen: It is a light-sensitive device and it is touched to the CRT screen where it can detect, a raster on the screen as it passes by and, with the help of this user can draw anything like lines, figures, or any objects.  1. Input Devices Microphone: It is a kind of voice input system that can be attached to a computer system to record sounds. It converts human speech or voice into electrical signals. This electrical signal is processed by the computer and the word is recognized. Optical Character Reader: It is used to detect alphanumeric characters that are written or printed on paper using a low-frequency light source. This light is absorbed by the dark areas and reflected by the light areas, now this reflected light is received by the photocells. It is like a scanner.  1. Input Devices Bar Code Reader: It is used to read bar codes and convert them into electric pulse which will further processed by the computer. Here, the barcode is data that is coded into white and black lines(or light and dark lines).  2. Output Devices These are the devices that are used to display the output of any task given to the computer in human-readable form. Some output devices: Monitor: The monitor is the main output device. It is also called VDU(visual display unit) and it looks like a TV screen. The Monitor displays the information from the computer. It is used to display text, video, images, etc. Printer: A printer is an output device that transfers data from the computer in a printed format by using text or images on paper. There are both colored and black & white printers. Further, there are also different types of printers, like Laser Printer, Dot-matrix printers, and Inkjet printers.  2. Output Devices Plotter: It is similar to a printer but potters are large in size. A plotter is used to generate large drawings, architectural blueprints, etc. on paper and these are high-quality images and drawings and large in size. Speakers: It is a very common output device and it gives sound as an output. Speaker is generally used to play music or anything having sound.  3. Storage Devices There are some devices that are used for storage purposes and are known as secondary storage devices. Some of them were: 1. CD (Compact disc): A CD is circular in shape and made up of thin platted glass and plastic polycarbonate material. It has a storage capacity of 600 MB to 700 MB of data. It has a standard size of 12 cm with a hole in the center of about 1.5 cm and 1.2 mm in thickness. There are basically 3 types of CDs, which are: CD-ROM (CD – Read Only Memory): Contents of this type of CD cannot be erased by the user. Only the publisher is allowed to access the data imprinted on this CD. CD-ROM is basically used for commercial purposes like for a music album or any application package by a software company.  3. Storage Devices CD-R (CD-Recordable): In this, content or data can be stored once. After that, they can be read many times but the data or content cannot be rewritten or erased. (Kind of one-time use) CD-RW(CD-Rewritable): As the name suggests, this type of CD is used to rewrite the content or erase previous content and again write new content many times.  3. Storage Devices 2. DVD (Digital Video/Versatile Disc): A DVD is the same as a CD but with some more features. A DVD comes in single and dual-layer formats. It has much greater storage capacity in comparison to CD. The storage capacity of a DVD with one-sided single layer is – 4.7 GB, one-sided double layer – 8.5 GB, double-sided single layer – 9.4 GB, and double-sided double layer – 17 GB. There are also some types in DVDs, which are : DVD-ROM: In this type, the contents of the DVD cannot be written on or erased by the user. DVD ROM is used for applications and database for distributing them in large amounts.  3. Storage Devices DVD-R / DVD+R: DVD-R (DVD minus R) and DVD+R (DVD plus R) are two different kinds of discs and they are once recordable format. Also, they have no difference virtually. DVD-RW / DVD+RW: This is a kind of rewritable disc and it allows up to 1,000 rewrites. DVD-RAM: DVD RAM is accessed like a hard disk. It provides high data security and storage capacity. This is a kind of rewritable disc and it allows up to 1,00,000 rewrites.  3. Storage Devices 3. Hard Disk: An hard disk is a non-volatile storage device that uses its read/write heads to store digital data on a magnetic surface of a rigid plate. It is generally 3.5 inches in size for desktops and 2.5 inches in size for laptops.  Hardware Components 1. CPU (Central Processing Unit) The CPU is also known as the heart of the computer. It consists of three units, generally known as the control unit, Arithmetic Logical Unit (ALU), and the memory unit. Below is the block diagram of the CPU is given: Hardware Components  Hardware Components As shown in the diagram input is given to the CPU through input devices. This input goes to memory and the control unit gets instructions from memory. The control unit now decides what to do with the input or instructions and transfers it to ALU. Now, ALU performs various operations like addition, subtraction, multiplication, division, logical operations, etc. After that, the final result gets stored in memory and finally passed to output devices to give the output. So, this is how the CPU works.  Hardware Components 2. Motherboard It is the main circuit board inside a computer and it contains most of the electronic components together. All the components of the computer are directly or indirectly connected to the motherboard. It includes RAM slots, controllers, system chipsets, etc.  Hardware Components 3. RAM (Random Access Memory) It is also known as temporary or volatile memory. It holds the program and data, which are currently in process or processing. All the data is erased as soon as the computer is turned off or in case of a power failure. Data stored in this memory can be changed.  Hardware Components There are two types of RAM:- 1. SRAM (Static RAM): SRAM basically consists of a flip- flop using a transistor or Mosfet (MOS). It is fast and has less access time. In this refreshing circuits are not required. But it is costly and requires more space. For e.g. cache memory. 2. DRAM (Dynamic RAM): DRAM consists of capacitors and the data is stored in the form of capacitors. Capacitors charge when data is 1 and don’t charge if data is 0. It requires refreshing circuits, as leakage of current in the capacitor can occur, so they need to be refreshed to the data. It is slower and has a higher access time. It is cheaper in comparison with SRAM. For e.g. Main memory.  Hardware Components 4. Video Graphics Array Port A video input commonly used on computer monitors is called a video graphics array (VGA) port. 5. Power Supply All of a computer system’s parts are powered by a power source. Typically, a power cord is used to connect a computer tower to an electrical outlet. The main function of the power supply is to convert AC voltage to dc voltages to power up the computer system.  Hardware Components 6. Cooling Fan A computer’s system to prevent overheating uses cooling fans. To aid customers who use their computers intensively, such as when streaming video or playing games, many computers contain more than one cooling fan. 7. Hard Drive On a computer system, files, programs, and other types of information are stored on hard drives, which are data storage devices. They utilise hard drives, which are magnetically coated discs used to store digital versions of information.  Software and its Types Software is a collection of instructions, data, or computer programs that are used to run machines and carry out particular activities. the software is basically a set of instructions or commands that tell a computer what to do.  Types of Software 1. System Software 2. Application Software System Software Operating System Language Processor Device Driver  Types of Software Application Software General Purpose Software Customize Software Utility Software System Software is software that directly operates the computer hardware and provides the basic functionality to the users as well as to the other software to operate smoothly. Or in other words, system software basically controls a computer’s internal functioning and also controls hardware devices such as monitors, printers, and storage devices, etc.  Types of System Software 1. Operating System: It is the main program of a computer system. When the computer system ON it is the first software that loads into the computer’s memory. Basically, it manages all the resources such as computer memory, CPU, printer, hard disk, etc., and provides an interface to the user, which helps the user to interact with the computer system. It also provides various services to other computer software. Examples of operating systems are Linux, Apple macOS, Microsoft Windows, etc.  Types of System Software 2. Language Processor: As we know that system software converts the human-readable language into a machine language and vice versa. So, the conversion is done by the language processor. It converts programs written in high- level programming languages like Java, C, C++, Python, etc(known as source code), into sets of instructions that are easily readable by machines(known as object code or machine code).  Types of System Software 3. Device Driver: A device driver is a program or software that controls a device and helps that device to perform its functions. Every device like a printer, mouse, modem, etc. needs a driver to connect with the computer system eternally. So, when you connect a new device with your computer system, first you need to install the driver of that device so that your operating system knows how to control or manage that device.  Application Software Software that performs special functions or provides functions that are much more than the basic operation of the computer is known as application software. Or in other words, application software is designed to perform a specific task for end-users. It is a product or a program that is designed only to fulfill end-users’ requirements. It includes word processors, spreadsheets, database management, inventory, payroll programs, etc.  Types of Application Software There are different types of application software and those are: 1. General Purpose Software: This type of application software is used for a variety of tasks and it is not limited to performing a specific task only. For example, MS-Word, MS-Excel, PowerPoint, etc. 2. Customized Software: This type of application software is used or designed to perform specific tasks or functions or designed for specific organizations. For example, railway reservation system, airline reservation system, invoice management system, etc.  Types of Application Software 3. Utility Software: This type of application software is used to support the computer infrastructure. It is designed to analyze, configure, optimize and maintains the system, and take care of its requirements as well. For example, antivirus, disk fragmenter, memory tester, disk repair, disk cleaners, registry cleaners, disk space analyzer, etc.