Learning Objectives• Introduce what computers are• Understand how computers evolved• How computer are categorised into broader classifications• Understand the complete architecture of a computer• Understand various components of a computer• Role of software and different types of software• Broader steps required in software development and implementation• Emerging trends in the world of computers
What is a Computer System?• A Computer is an electronic device that operates under the control of a set of instructions that is stored in its memory unit.• A computer accepts data from an input device and processes it into useful information which it displays on its output device.• A computer system is a collection of hardware and software components that help in accomplish many different tasks.• Hardware consists of the computer itself, and any equipment connected to it. Hardware includes all of the physical, tangible parts of a system – such as central processor, memory, display devices, storage media and printer etc.• Software is the set of instructions for controlling the hardware devices, instructing computers to transform data into information and many other information processing tasks.
• Generation of Computers First Generation – Vacuum Tubes (1939-1959): These computers were powered by thousands of vacuum tubes. The Z1, Z3 and UNIVAC I are some examples. First generation computers were very slow, consumed huge amount of power and had poor reliability accuracy.• Second Generation – Transistors (1959-1965): These computers were made of transistors. Transistors controlled the flow of electricity through the circuits. The use of transistors was a breakthrough in technology that allowed computers to become physically smaller and more powerful, more reliable, and even faster.• Third Generation – Integrated Circuits (1965-1971): These computers used integrated circuits (ICs). Integrated Circuits were also smaller, more efficient, and more reliable as compared to Vacuum tubes and Transistors. Third generation computers used secondary storage devices, such as magnetic tapes, magnetic disks, which are located outside the computer. The use of faster input/output devices contributed to the enhanced utility of these computers for multiprogramming, wherein a number of programs could be executed simultaneously by a single computer.• Fourth Generation – PCs and VSLI (1971-1991): Fourth generation is the generation of Large-Scale Integration (LSI) of chips with several thousand transistors and Microprocessors (based on Very-Large- Scale Integration (VLSI)). Microcomputers were developed which allowed home and business users to adapt computers for word processing, spreadsheet, file handling, graphics, and much more.• Fifth Generation – Artificial Intelligence and Internet (1991 till date): The fifth generation computers are more intelligent and have “thinking” power and capacity to take decisions. The concept of Artificial Intelligence (AI) is being used in these computers and the processors used are known as `Knowledge Processors’. Grand scale integration (GSI) happened, which allowed over thousand million transistors embedded on a single chip. The GSI, allowed the computer to perform teraflop (trillion floating point processing per second) of data. Fifth generation also introduced the concept of parallel processing, which was the necessity of AI to happen.
Classification of Computers• Computers are available in different shapes, sizes, processing capacities and weights, due to these different shapes and sizes they perform different types of jobs and have different functionalities. – Supercomputer – Mainframe – Micro-computer – Notebook – PDAs
Components of a Computer System• Central Processing Unit (CPU): The “brain” of the Computer – this is where the actual computing is done. The CPU usually controls all the operations of the computer.• Memory: An electronic storage medium used to hold the program which instructs the CPU and other components of the computer.• Input/Output Devices: These are the link between man and machine. They depend on the processing requirements.• Input/ Output Interfaces: These are `middleman` between the CPU and the I/O devices. They provide the actual hard-wired control of the I/O devices, according to the commands that are issued by the CPU.• Programs (Software): Without the program, a computer is a dumb machine that sits there and draws current. The program coordinates the operations of the computer in order to perform some desired process.
Central Processing Unit (CPU)Clock Micro-Processor Chip ROM Storage RAM Storage Input Output (I/O) Interface Control Bus Address Bus Data Bus
Components of a Computer• Central Processing Unit: The central processing unit is the most important part of a computer system. It is also referred as a "brain" of the computer.• Arithmetic and Logic Unit: The arithmetic and logic unit (ALU) is the part of the CPU where all mathematical and logical functions are performed.• Control Unit: The control unit interprets any instruction it receives from memory and directs the sequence of events necessary to execute the instruction.• Primary Storage: The primary storage unit refers to the internal storage of the computer, where programs and their data are stored.• Bus: A bus is simply an electrical path on which data can flow from point to point within a circuit.
Memory• Random-access memory (RAM) is that part of primary storage where data and program instructions are held temporarily while being manipulated or executed.• Read-Only Memory (ROM), as the name implies, the contents of ROM can be read only; data cannot be written into it.• Cache Memory• Dynamic random access memories (DRAMs)• Synchronous DRAM (SDRAM)
Input Devices• An input device is a peripheral device through which data are entered and transformed into machine-readable form. Some of the commonly used input devices are: – Keyboards – Mouse – Light Pens and Digitizers – Voice Recognitions – Magnetic-Ink Character Recognition -Optical Scanners – Web Camera – Secondary Storage media like CD, DVD etc.
Output Devices• An output device is a peripheral device that accepts data from a computer and transforms them into a usable form, thus allowing the computer to communicate information to humans or other machines. Commonly used output devices are: – Printers – Plotters – Monitors and Terminals – Speakers – Secondary Storage media like CD, DVD etc.
Secondary Storage• Secondary storage is the non-volatile memory that supplements main memory by providing data storage that is permanent and typically of much greater capacity than main memory. It is less expensive, as compared to the primary storage and is usually used for storage of large amounts of data for permanent storage. Secondary storage is also used for storing backups, or copies, of data and programs that are frequently required at a later date. Commonly used secondary storage devices are: – Magnetic Tapes – Magnetic Disks – Optical Disks
Computer Software• The set of instructions used to control hardware and accomplish specific tasks are called software. Computer software provides the logic that drives computer hardware.• The major functions of software are to: – manage the computer resources of the organisation; – develop tools that human beings can utilize to take advantage of these resources; and – act as an intermediary between stored information and organisations.
Type’s of Software• System Software: System software directly interacts with the hardware and comprises of programs that manage the hardware components.• Application Software: Programs that help the user, the system software, and the hardware work together to solve end-user problems are application software.• Applications software can be purchased in stores and is called packaged or commercial software.• Packaged software can be purchased, or in some cases, it is available free of cost called Freeware
Software Generations• The first generation (1940s) of software was the machine language, which used the 0s and 1s of binary language and was the only way in which programmers could communicate with the computer.• The second generation (1950s) of software was the development of assembly language - using mnemonic codes.• The third generation (1950-70s) of software was the development of first high level languages - more sophisticated extensions of assembly language and used more English like sentences.• Fourth generation (1970s) of software development was of packaged software programs that perform limited functions. These programs reduced the need of writing and compiling small routine applications.• Fifth generation (1990s) of software development was of integrated software, animations software and multimedia technology. Natural languages is also treated as part of fifth-generation languages
Operating Systems• An operating system is a set of programs that controls and supervises a computer system’s hardware and provides service to application software, programmers, and users of a computer system.• The purpose of an operating system is to manage the hardware resources efficiently and to provide an interface between the hardware and an application program and end user.• An operating system helped in increasing the efficiency of a CPU, it decides which resources will be used, which programs will run, and how the programs will be translated into machine language.• Major Goals of Operating System: – To hide details of hardware by creating abstraction – To allocate resources to processes (Manage resources) – Provide a pleasant and effective user interface
Control and Processing Programs• Control programs manage the computer hardware and resources. The major functions of these programs are: – resource management – data management – job (task) management• Processing programs are programs in the operating system that provide a service to the user or the programmer of the computer system. Examples includes: – language-translator programs – utility programs
Types of Operating Systems• Single-User Operating System• Multi-user Operating System• Multiprogramming Operating System• Time-sharing Operating System• Multiprocessing Operating System• Virtual-storage Operating System• Virtual-Machine Operating System• Mobile Operating System
Types of Information Processing• Batch Processing• Real-time Processing• Distributed Processing• Parallel Processing – Sequence scheduling – Concurrent scheduling
Application Software• Application software is any tool that helps in solving end-user problems. It includes the generic productivity software like spreadsheets, word processors, database programs, email as well as custom and packaged programs for payroll, billing, inventory and other accounting purposes.• There are different types of application software, which can be classified as per broader classifications: – Content Access Software – End-User Software – Enterprise Software – Simulation Software
Industry Trends• DNA COMPUTING• Nanotechnology• WEARABLE COMPUTING• EMBEDDED COMPUTERS, Optoelectronic computers and Quantum computing.• Componentware• Services-oriented architecture (SOA• Autonomic Computing• Grid Computing• Cloud Computing• Content and content
Summary• Computer is an electro-mechanical device that helps is storing and processing data for business purpose.• All computers, irrespective of size and power, include a CPU, one or more input units and output units, secondary storage and software.• A central processing unit (CPU) is comprised of an arithmetic and logic unit (ALU), a control unit, and a primary storage unit.• Modern technology has put the ALU, the control unit, and in some cases, the primary storage unit onto one integrated circuit called a microprocessor.• There are several forms of primary storage, including semiconductor memory - RAM and ROM.• RAM is a volatile memory and are used primarily for temporary storage.• ROM is non-volatile and is used for permanent storage.• Data are transferred out of memory and into the ALU for processing by way of the control, address, and data buses.• The process of executing an instruction involves both an instruction cycle and an execution cycle.• The process of entering and translating it into machine readable form is called input.• The process of translating machine-readable data into a human readable format is called output.
Summary• Primary storage is often inadequate because of its limited size and its volatility. To supplement primary storage, secondary storage-a memory that is external to the computer and non-volatile.• Three types of secondary storage media are magnetic tapes, disks, and optical media.• A program, or software, is the series of instructions that directs the hardware to perform various tasks.• System software and application software are the two major categories of the software. Each of these serves a different purpose.• The set of programs that controls a computer systems hardware and provides services to users of the system is called an operating system. It is composed of two types of programs: control and processing programs. Control programs manage the computer hardware and resources. Processing programs provide a service to the user or programmer of a computer system.• In order to instruct a computer to perform specific tasks, a set of written codes is called a programming language.• Different types of Programming languages that exists can be categorised as: machine, assembly, high-level, fourth-generation languages and object-oriented languages.• An application package is a program that interacts with the system software to direct the computer hardware to complete a task for the user. Commonly used application software are word processor, spreadsheet, database, presentation tools, communication software, accounting and financial software and project management.• Software programs can be developed in-house or can be procured from the software vendor. While procuring the software, different options that are available include shareware, freeware, open source and public domain. One needs to be clear about these options and use them appropriately. One also needs to be clear about the need of the user and the organisations objectives while procuring the software.