Computer Systems PDF

Computer Systems Hardware, Software and Peopleware Hardware Hardware The physical components of computer system. It refers to the tangible devices that can be seen, touched and felt. Computer Systems Physical Components Five Categories 1. Input Devices 2. System Unit 3. Secondary Storag...

Computer Systems Hardware, Software and Peopleware Hardware Hardware The physical components of computer system. It refers to the tangible devices that can be seen, touched and felt. Computer Systems Physical Components Five Categories 1. Input Devices 2. System Unit 3. Secondary Storage 4. Output Devices 5. Communication Devices 1) Input Devices Translate data and programs that humans can understand into a form that the computer can process. Computer Systems Input Devices Examples: Keyboard Looks like a typewriter keyboard, but has additional specialized keys. Computer Systems Input Devices Keyboard Input Devices Examples: Mouse Is a pointing device that typically rolls on the desktop. It directs the insertion point or cursor on the display screen. Has one or more buttons for selecting commands Also used for drawing figures. Computer Systems Input Devices Mouse 2) System Unit Is the electronic circuitry housed within the computer cabinet. The two of the most important components of the system unit are: Central processing Unit (CPU) Control Unit Central Processing Unit Controls and manipulates data to produce information. A microcomputers CPU is contained on a single integrated circuit or microprocessor chip. The brain of the computer. It also thinks for the computer with the help of the human using it. Performs calculations, compares data and produces results. It has two components: the control unit and arithmetic- logic unit Central Processing Unit performs all the calculations, makes decisions, and carries out instructions from programs and users. Ex: Conductor of an Orchestra Central Processing Unit Control Unit Components of CPU tells the rest of the computer system how to carry out a program’s instructions. directs the movement of electronic signals between memory and the arithmetic logic unit it also directs these control signals between the CPU and input and output devices Control Unit Ex: CPU is a busy workplace Control Unit is the manager – The Control Unit tells other parts what to do, when to do it and how to do it. By this it ensures to run different parts of a computer to run smoothly and correctly. Control Unit Arithmetic-Logic Unit Components of CPU called ‘ALU’ 2 TYPES OF OPERATIONS: Arithmetic Operations: addition, subtraction, multiplication and division. Logical operations consist of comparisons. That is, two pieces of data are compared to see whether one is equal to (=), less than () the other. 3) Memory ( Primary Storage or Random Access Memory) Main memory (internal storage) Holds data and program instructions for processing the data. It holds the processed information before its output. It is sometimes referred to as temporary storage. It is located in the system unit on tiny memory chips. Memory ( Primary Storage or Random Access Memory) Secondary Storage It also holds data and programs permanently. It supports the main memory. It stores data and programs for future use. This type of memory stores the information on storage media such as floppy disks and CDs Floppy disks ( also known as diskettes) widely used to store and transport data from one computer to another. called as floppy disk because data is stored on a very thin flexible or floppy plastic disk. Floppy disks ( also known as diskettes) Hard disks - HDD are typically used to store programs and very large data files. Have a much greater capacity and are able to access information much faster than floppy disks. Hard disks Optical disks is relatively new and evolving format Use laser technology and have the greatest capacity. Two basic formats: CD and DVD Optical disks Optical disks CD - Compact Disc DVD - Digital Versatile Disc CD (Compact Disc) used to distribute large databases and reference, to back up large data source, and to create, store and edit multimedia presentation. -Audio Recordings DVD ( Digital Versatile Disc or Digital Video Disc) capacity is far greater than CDs. can be used for all the things that CDs are used for, plus they are used to distribute full length motion pictures. Blu-ray Disc high-definition offers much higher storage capacity compared to CDs and DVDs. can store 25 GB of data, and dual-layer discs can hold up to 50 GB. 1.Fetching Instructions: The Control Unit fetches instructions from main memory. It does this by sending a memory address to RAM that points to the location of the next instruction to be executed. 2.Decoding Instructions: Once the instruction is fetched, the Control Unit decodes it to understand what operation needs to be performed and what data is required. 3.Executing Instructions: Depending on the instruction, the Control Unit directs the ALU to perform the necessary arithmetic or logic operation using data from registers. For data that is not in registers, the Control Unit may need to fetch additional data from main memory. 4. Storing Results: After the ALU completes its operation, the results can be stored back in registers or written to main memory, depending on the instruction's requirements. 5. Next Instruction: The Control Unit repeats this process for each instruction in the program, ensuring that they are executed sequentially. The Control Unit fetches instructions from main memory, decodes them, and coordinates the execution of these instructions by directing the ALU. The ALU performs the necessary arithmetic and logic operations on data, and the results are then either stored back in registers or written to main memory. These three components work in tandem to execute program instructions and perform computations within a computer's CPU. 4) Output Devices Are pieces of equipment that translate the processed information from the CPU into a form that humans can understand. Example: Monitor, Printer Monitor or video display Resembles a television screen. screen It displays the result of different commands given by the user. It shows how the computer answers the commands and show results of what you are doing. The output seen in the monitor is called as softcopy Printer a device that produces printed paper output. it produces images on paper which have created in a computer. the printed output is called as hardcopy 5) COMMUNICATIONS DEVICE hardware devices or equipment that enable the transmission, reception, and exchange of data, information, or signals between individuals or systems. Examples: Smartphone Landline Telephones Modem Wireless Router Webcam Software Software another name for programs. it includes instructions that tell the computer how to process data is a set of programs or procedures associated with the computer system. 2 Kinds of Software System Software Application Software 1. System Software Is background software that helps a computer manage its internal resources. are programs designed to directly or indirectly support program processing. Consists of utilities, device drivers, language translators, and operating systems. deals with the physical complexities of computer hardware. Operating System Is a group of computer programs that help your software control your hardware. Example: IOS, Linux, Ubuntu, Windows 2.Application Software also known as the basic applications Performs useful work on general purpose problems. Designed to be used by many people to do the most common kinds of tasks. 2 Types of Application Software Basic Applications Advanced Applications Basic Applications Browsers: used to connect to remote computers, open and transfer files, display text and images, and provide an interface to the Internet and the Web. Word Processor: used to create, edit, save, and print text-based documents. Spreadsheet: used to analyze, organize, manipulate and graph numeric information. Basic Applications Database management system: organize and manage data and information. Presentation graphics: are use to create professional and exciting presentations Advanced Applications Multimedia: integrate video, music, voice, and graphics to create interactive presentations. Web publishers: create interactive multimedia Web pagesgraphics programs: create professional publications, draw, edit, and modify images. Advanced Applications Virtual Reality: create realistic three – dimensional virtual or simulated environments. Artificial Intelligence: simulated human thought processes and actions. Project Managers: plan projects, schedule, people , and control resources Peoplewar e Peopleware The people involved in the data processing cycle. known as the users or end users -any person who can manipulate and use the computer system and its programs. DATA Data consists of the raw, unprocessed facts. Information Processed data