03 - Fundamental 3 for programming computing, Study Guides, Projects, Research of Programming Languages

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Lecture 03: Operating

System

Objectives

• (^) Explain the basic role of an operating system in modern-day

computers

• (^) Explain the general functions and components of an operating system
• (^) Discuss the interfacing between the operating system and application

program or the user

• (^) Trace the history of the development of operating systems
• (^) Explain the different types of operating systems
• (^) Get an overview on some operating systems such as unix and msdos

1. Introduction

• (^) Computer software can be divided roughly

into two parts: system programs, which

manage the operation of the computer itself,

and application programs, which perform the

actual work the user wants. The most

important system program is the operating

system (OS) that controls all the computer

resources and provides the base upon

which the application program can be written

1. Introduction

• (^) One of the major functions of the operating system is to hide all this complexity and give the programmer a more convenient set of instructions to work with.

2. Introduction to Operating System

• (^) An operating system is also a control program. It controls the execution of user programs to prevent errors and improper use of the computer. Therefore, it may be defned as follows: An operating system (OS) refers to the software on a computer that lets it run applications, control peripherals, and communicate with other computers

5.3 Functions of an operating system

• (^) Process management
• (^) The operating system is responsible for the following activities with respect to process management: The creation and deletion of user and system processes The suspension and resumption of processes Keep track of the resources (processors and the status of processes). Allocate the resources to a process by setting up the necessary hardware reclaim the resources when the process relinquishes processor usage, terminates, or exceeds the allowed amount of usage The provision of mechanisms for process synchronization—decide which process gets the processor, when, and for how much time The provision of mechanisms for deadlock handling

5.3 Functions of an operating system

• (^) Secondary memory management
• (^) The operating system is responsible for the following activities for accomplishing the disk management functions: +Free space management +Storage allocation +Disk scheduling
• (^) Device (I/O) management One of the purposes of an operating system is to hide the peculiarities of specifc hardware devices from the user

• A buffer memory system
• A general device driver program
• Drivers for specifc hardware devices

5.3 Functions of an operating system

• (^) File management
• (^) The operating system is responsible for the following activities for accomplishing the fle management functions:
  • Creation and deletion of fles
  • Creation and deletion of directory
  • Support of primitives for manipulating fles and directories
  • Mapping of fles onto disk storage
  • Backup of fles on stable (non-volatile) storage

5.4 Components of an operating system

• (^) Command interpreter
• (^) Many commands are given to the operating system by control statements. A program that reads and interprets control statements is automatically executed. This program is variously called (a) the control card interpreter, (b) the command line interpreter, (c) the shell (in UNIX), and so on. Its function is quite simple: it gets the command statement and executes it

5.4 Components of an operating system

• (^) Kernel: Kernel is a core part of the operating system and is loaded on the

main memory when it starts up. It is the core library of functions; the operating

system ‘knows’. In the kernel, there are the functions and streams to

communicate with the system’s hardware resources

The main functions of the kernel are as follows:

+ To provide a mechanism for the creation and deletion of processes

+ To provide Cpu scheduling, memory management, and device management

for these processes

+ To provide synchronization tools so that the processes can synchronize their

actions

+ To provide communication tools so that processes can communicate with each

other

5. Interaction with Operating System

• (^) System calls
• (^) System calls provide the interface between a running program and the operating system. These calls are generally available as assembly language instructions, and are usually listed in the manuals used by assembly language programmers

5. Interaction with Operating System

• (^) Operating system commands Apart from system calls, users may interact with the operating system directly by means of commands. For example, if the user wants to list fles or sub-directories in MsDOs, the DIR command is invoked

6.1 First generation (1945–55)

• (^) The first generation marked the beginning of commercial computing, including the introduction of eckert’s and Mauchly’s univac I in early 1951, and a little later, the IBM 701, also known as the Defense Calculator. The first generation computer was characterized by the vacuum tube as the active component technology
• (^) This mode of computer operation was called ‘closed shop’ and was marked by the appearance of hired operators who would select the job to be run, then load the program in the system, run the program, select another job, and so on

6.2. Second generation (1956–63) transistors and Batch system

• (^) Transistors replaced vacuum tubes as the hardware component technology in the second generation of computer hardware. In addition, some very important changes in hardware and software architectures occurred during this period. For the most part, computer systems remained card- and tape-oriented systems. Signifcant use of random access devices, that is, disks, did not appear until the end of the second generation. program processing was, mostly, provided by large, centralized computers operated under monoprogrammed batch processing operating systems