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INTRODUCTION TO OPERATING SYSTEMS
Transcript of INTRODUCTION TO OPERATING SYSTEMS
The 1960's definition of an operating system is "the software that controls the hardware"
is a of programs containing instructions that coordinate all activities among computer hardware resources.
It acts as intermediary between the user of a computer and the computer hardware.
it also provides a user-friendly environment in which a user may easily develop and execute a program.
Primary goal of an Operating System
is to make the computer system convenient to use.
is to use the computer hardware in an efficient manner.
Functions of an Operating Systems
It provides services to programs and users of that programs that would make programming easier, convenient and efficient.
It attempts to schedule computational activities to ensure good and correct performance of the computing system as it place them in and out of the memory.
It interprets the different commands that the user enter at the keyboard and could translate them into actions.
It schedules and supervises the simultaneous execution of several programs.
tasks of an operating system
the process management activities handled by the OS are
control access to shared resources like file, memory, I/O, CPU
control execution of applications,
create, execute and delete a process
cancel or resume a process
schedule a process
and deadlock handling for process.
Memory is central to the operation of modern computer system. The activities of memory management handled by OS are:
to a program when a used block is freed
keep track of
File Management is one of the most visible services of an OS. the management task include: create and delete both files and directories, provide access to files, allocate space for files, keep back-up for files and secure files,
Programs that computer execute, together with the data computer accesses, must be in main memory during execution. But then the main memory is too small to permanently accommodate all data and programs, the computer system must provide secondary storage to back-up main memory.
Protection and Security
Protection refers to a mechanism for controlling the access of programs, processes, or users to the resources defined by a computer controls to be imposed, together with some means of enforcement.
User interface or Command Interpreter
A user interface provides a consistent way of interaction between user and the computer system. The OS acts as an engine to provide means of interaction between user and computer through the user interfaces.
The device management tasks handled by OS are-
open, close and write device drivers, and
communicate, control and monitor the device driver.
Types of operating system
Single User and Single Task Operating System
As the name implies, this operating system is designed to manage the computer so that one user can effectively do one thing at a time. It is for use by a single user for a standalone single computer for performing a single task. Single user OS are simple operating system designed to manage one task at a time. MS-DOS is an example of single user OS.
Single User and Multitasking Operating System
This is the type of operating system most people use on their desktop and laptop computers today. It allows execution of more than one task or process concurrently. For this, the processor time is divided amongst different tasks. This division of time is also called "time sharing". The processor switches rapidly between processes. Windows 95 and all newer versions of Windows are examples of multitasking OS.
Multiuser Operating System
A multi-user operating system allows many different users to take advantage of the computer's resources simultaneously. It is used in computer networks that allow same data and applications to be accessed by multiple users at the same time. Linux, UNIX, and newer version of Windows are the examples of multiuser OS.
Multiprocessing Operating System
It have two or more processors for a single running process. Processing takes place in parallel and is also called "parallel processing". Each processor works on different parts of the same task or on two or more different tasks. Linux, UNIX, Windows 7 are examples of multiprocessing OS.
Real Time Operating System
Real-time operating system are used to control machinery, scientific instrument and industrial systems. An RTOS typically has very little user-interface capability, and no end-user utilities, since the system will be a "sealed box" when delivered for use. RTOS are designed to respond to an event within a predetermined time. LynxOS is an example of real time OS.
Embedded Operating System
It is an OS that is already embedded in a device in the ROM. They are specific to a device and are less resource intensive. They are used in appliances like microwaves, washing machines, traffic control systems etc.
History of operating System
The 1940's- First Generation
The earliest electronic digital computers has no operating system. Machines of the time were so primitive that programs were often entered one bit at time on rows of mechanical switches. Programming languages were unknown. Operating systems were unheard of.
The 1950's- Second Generation
By the early 1950's, the routine had improved somewhat with the introduction of punch cards. The General Motors Research Laboratories implemented the first operating system in early 1950's for their IBM 701. The system of the 50's generally ran one job at a time. These were called single-stream batch processing systems because programs and data were submitted in groups or batches.
The 1960's- Third Generation
The systems of the 1960's were also batch processing systems, but they were able to take better advantage of the computer's resources by running several job at once. So operating systems designers developed the concept of multiprogramming in which several jobs are in main memory at once.
With the development of LSI (Large Scale Integration) circuits, chips, operating system entered in the system entered in the personal computer and the workstation age. Microprocessor technology evolved to the point that it becomes possible to build desktop computers as powerful as the mainframes of the 1970's. Two operating systems have dominated the computer scene: MS-DOS written by Microsoft Inc. for the IBM PC and the other machines using the intel 8088 CPU, and UNIX using Motorola 6899 CPU family.
7 steps of Booting
is the process of starting or restarting a computer.
Is when you turn on your computer after it has been powered off completely.
Is the process of restarting a computer that is powered on.
The power supply sends a signal to the components in the system unit.
The processor looks for the BIOS
The BIOS, which stands for Basis Input Output System, is a firmware that contains the computer's start up instructions.
The BIOS performs the POST to make sure that the computer hardware is connected properly and operating correctly.
The power-on self test (POST) checks the various system components, such as mouse, keyboard connectors and expansion cards. As the POST, executes, LED flicker on devices, including the disk drives and keyboard.
The POST results are compared with data in the CMOS chip.
The BIOS looks for the system files in the hard disk drive (Drive C:\)
The boot program loads of the operating system into memory (RAM) and execute.
The operating system loads configuration information and displays the desktop screen.
the user interface
The user interface is provided to control how you enter data and instruction and how information displays on the screen.
major types of
Command Line Interface (CLI)
A type of user interface wherein the user enters the commands at the keyboard and the programs responds by operating in a specific manner. Example: MS-DOS
A type of user interface wherein the commands for the programs are typically given via menu selections. It offers the user a choice of command words that can be activated by typing a letter, pressing a direction key or pointing with a mouse.
Graphical User Interface (GUI)
A type of interface wherein the programs and commands are represented in a graphical forms called icons. A good example of this type of user interface is Microsoft Windows.
Voice Operated Interface
It explores the concept of a hand held computer that has no keyboard or visual display, but uses a speech interface instead. Information is stored in an audio format, as opposed to text, and accessed by issuing spoken commands instead of typing.
Web-Based User Interface
Accept input and provides output by generating web pages which are transported via internet and viewed by the user using a web browser program.
Touch Interface / Point User Interface (PUI)
Touch interface are graphical user interface using touch screen display as a combined input and output device. Used in vertical market appliances, self-service machines, tablet PCs, mobile devices, etc.
Gestures interface are graphical user interface, which accept input in a form of hand gestures, or mouse gestures sketched with a computer mouse or a stylus.