OPERATING SYSTEM Neethu Narayanan Assistant Professor Department of

OPERATING SYSTEM Neethu Narayanan Assistant Professor Department of Vocational Studies St. Mary’s College, Thrissur

OPERATING SYSTEM v System software is a type of computer program that is designed to run a computer’s hardware and application program. If we think of the computer system as a layered model, the system software is the interface between the hardware and user applications. v The operating system (OS) is the best-known example of system software. The OS manages all the other programs in a computer. Operating System, Neethu Narayanan, St. Mary's College, Thrissur

TYPES OF SYSTEM SOFTWARE 1. 2. 3. OPERATING SYSTEM LANGUAGE PROCESSOR DEVICE DRIVERS Operating System, Neethu Narayanan, St. Mary's College, Thrissur

LANGUAGE PROCESSOR v Assembly language is machine dependent yet mnemonics that are being used to represent instructions in it are not directly understandable by machine and high Level language is machine independent. Operating System, Neethu Narayanan, St. Mary's College, Thrissur

LANGUAGE PROCESSOR v A computer understands instructions in machine code, i. e. in the form of 0 s and 1 s. It is a tedious task to write a computer program directly in machine code. The programs are written mostly in high level languages like Java, C++, Python etc. and are called source code. Operating System, Neethu Narayanan, St. Mary's College, Thrissur

LANGUAGE PROCESSOR v These source code cannot be executed directly by the computer and must be converted into machine language to be executed. Hence, a special translator system software is used to translate the program written in high-level language into machine code is called Language Processor and the program after translated into machine code (object program / object code). Operating System, Neethu Narayanan, St. Mary's College, Thrissur

LANGUAGE PROCESSOR The language processors can be any of the following three types: 1. Compiler – The language processor that reads the complete source program written in high level language as a whole in one go and translates it into an equivalent program in machine language is called as a Compiler. Example: C, C++, C#, Java. Operating System, Neethu Narayanan, St. Mary's College, Thrissur

LANGUAGE PROCESSOR Ø In a compiler, the source code is translated to object code successfully if it is free of errors. The compiler specifies the errors at the end of compilation with line numbers when there any errors in the source code. The errors must be removed before the compiler can successfully recompile it. Operating System, Neethu Narayanan, St. Mary's College, Thrissur

LANGUAGE PROCESSOR 2. Assembler – The Assembler is used to translate the program written in Assembly language into machine code. The source program is a input of assembler that contains assembly language instructions. The output generated by assembler is the object code or machine code understandable by the computer. Operating System, Neethu Narayanan, St. Mary's College, Thrissur

LANGUAGE PROCESSOR 3. Interpreter – The translation of single statement of source program into machine code is done by language processor and executes it immediately before moving on to the next line is called an interpreter. If there is an error in the statement, the interpreter terminates its translating process at that statement and displays an error message. The interpreter moves on to the next line for execution only after removal of the error. Operating System, Neethu Narayanan, St. Mary's College, Thrissur

LANGUAGE PROCESSOR Ø If there is an error in the statement, the interpreter terminates its translating process at that statement and displays an error message. Ø The interpreter moves on to the next line for execution only after removal of the error. Ø An Interpreter directly executes instructions written in a programming or scripting language without previously converting them to an object code/ machine code. Example: Perl, Python and Matlab. Operating System, Neethu Narayanan, St. Mary's College, Thrissur

DEVICE DRIVERS Ø A device driver is a particular form of software application that is designed to enable interaction with hardware devices. Without the required device driver, the corresponding hardware device fails to work. Operating System, Neethu Narayanan, St. Mary's College, Thrissur

DEVICE DRIVERS Ø More commonly known as a driver, a device driver or hardware driver is a group of files that enable one or more hardware devices to communicate with the computer's OS. Without drivers, the computer would not be able to send and receive data correctly to hardware devices, such as a Printer Operating System, Neethu Narayanan, St. Mary's College, Thrissur

DEVICE DRIVERS Ø A device driver usually communicates with the hardware by means of the communications subsystem or computer bus to which the hardware is connected. Device drivers are operating system-specific and hardware-dependent. A device driver acts as a translator between the hardware device and the programs or operating systems that use it. Ø A device driver may also be called a software driver. Operating System, Neethu Narayanan, St. Mary's College, Thrissur

OPERATING SYSTEM Ø An operating system is a program that acts as an interface between the software and the computer hardware. Ø It is an integrated set of specialized programs used to manage overall resources and operations of the computer. Ø It is a specialized software that controls and monitors the execution of all other programs that reside in the computer, including application programs and other system software. Operating System, Neethu Narayanan, St. Mary's College, Thrissur

OBJECTIVES Ø Convenience Ø Increase work efficiency Ø Ability to create new function Figure: - Overview of Operating System, Neethu Narayanan, St. Mary's College, Thrissur

FUNCTION OF OPERATING SYSTEM Process Management: The Process Management means all the Processes those are given by the user or the Process those are System ‘s own Process are Handled by the Operating System. The Operating System will Create the Priorities for the user and also Start or Stops the Execution of the Process and Also Makes the Child Process after dividing the Large Processes into the Small Processes Operating System, Neethu Narayanan, St. Mary's College, Thrissur

FUNCTION OF OPERATING SYSTEM Memory Management: Operating System also Manages the Memory of the Computer System means Provide the Memory to the Process and Also Deallocate the Memory from the Process. And also defines that if a Process gets completed then this will deallocate the Memory from the Processes Operating System, Neethu Narayanan, St. Mary's College, Thrissur

FUNCTION OF OPERATING SYSTEM Input/output Management : Input devices are used to get information into a computer system, and include peripheral devices like the keyboard and mouse now found attached to virtually all computer systems. Output devices receive information from a computer, and include devices such as monitors and printers. Some input and output (I/O) devices can be used for input and output, including network adapters and secondary storage devices. Operating System, Neethu Narayanan, St. Mary's College, Thrissur

FUNCTION OF OPERATING SYSTEM Devise Management : Keeps track of all the devices. This is also called I/O controller that decides which process gets the device, when, and for how much time Operating System, Neethu Narayanan, St. Mary's College, Thrissur

FUNCTION OF OPERATING SYSTEM Security Management The security management function of an operating system helps in implementing mechanisms that secure and protect the computer system internally as well as externally. Therefore an operating system is responsible for securing the system at two different levels which are internal security and external security. Operating System, Neethu Narayanan, St. Mary's College, Thrissur

FUNCTION OF OPERATING SYSTEM Ø Internal security: Internal security refers to the protection of activities of one process from the activities of another process. The term internal security may also be regarded as system protection. The internal security of the computer system also ensures the reliability of the computer system. There may be a number of process running in the computer systems use the concept of least privilege to implement internal security. Operating System, Neethu Narayanan, St. Mary's College, Thrissur

FUNCTION OF OPERATING SYSTEM for Ø External security: External security refers to the implementation of a mechanism the computer system as well as the various resources of the computer system against unauthorized access. The term external security may also be regarded as system security. External security is particularly required when a computer system is either on a network or connected to the internet. Operating System, Neethu Narayanan, St. Mary's College, Thrissur

REFERENCE Ø www. cl. cam. ac. uk Ø http: //iips. icci. edu. iq/images/exam/Abraham-Silberschatz. Operating-System-Concepts Operating System, Neethu Narayanan, St. Mary's College, Thrissur