1 - Introduction to OS.pdf

Introduction to Operating System Ms. Nancy D. Delos Santos – Rodriguez Instructor Pre-Assessment Activity Please see the link to your pre-assessment activity in Google Classroom  Objectives Identify the Components of a computer system Define Operating System Giv...

Introduction to Operating System Ms. Nancy D. Delos Santos – Rodriguez Instructor Pre-Assessment Activity Please see the link to your pre-assessment activity in Google Classroom  Objectives Identify the Components of a computer system Define Operating System Give the functions and services provided by Operating Systems Identify the types of Operating Systems Understand how Operating Systems evolved 3  Computer System Structure Computer system can be divided into four components – Hardware – provides basic computing resources CPU, memory, I/O devices – Operating system – Controls and coordinates the use of the hardware among various applications and users – Application programs – define the ways in which the system resources are used to solve the computing problems of the users Word processors, compilers, web browsers, database systems, video games – Users People, machines, other computers 4 Components of a Computer System 5 What is an Operating System An OS is just another kind of program running on the CPU – It has a main() function that gets called only once (during boot) – Like any program, it consumes resources (such as memory) But it is a very sophisticated program: – It is not supposed to terminate – It can execute any instruction in the machine Traditionally written in assembly language, operating systems can now be written in higher-level languages. 6 What is an Operating System? It is a program that acts as an interface between computer system users and the computer hardware. It provides a convenient and user-friendly environment in which a user may easily develop and execute programs. It hides the complexity of hardware from uninterested users. 7 What is an operating system? The software which manages the overall operation of the computer system including: hardware (CPU, RAM, I/O) security system interface application interface 8 The kernel The operating system file (program) which is copied into RAM, usually from the hard disk drive, during boot-up. The kernel remains in RAM while the computer is on and is in charge of the overall operation of the computer system. The internal component of an OS that performs the basic functions required by the computer. “The one program running at all times on the computer” Everything else is either a system program or an application program Also called the “nucleus” – kmem (Linux) – command.exe (Microsoft) 9 How do you start the OS? Booting – the act of starting up a computer by loading the kernel. Bootstrap program – code stored in ROM (generally known as firmware) loaded at power-up or reboot that is able to locate the kernel, load it into memory, and start its execution. 10  How do you start the OS? Your computer has a very simple program pre-loaded in a special read-only memory – The Basic Input/Output System, or BIOS When the machine boots, the CPU runs the BIOS The BIOS, in turn, loads a “small” OS executable – From hard disk, CD-ROM, or whatever – Then transfers control to a standard start address – The small version of the OS loads and starts the “big” version 11 The functions of an operating system 1. Manages and Interacts with Computer Hardware 2. Provides and Manages System Security 3. Provides the System Interface 4. Provides the Interface for Application Software 12 1. Manages and Interacts with Computer Hardware Manages the CPU Manages RAM - OS will send a message when RAM is full 13  1. Manages and Interacts with Computer Hardware Provides an interface for storage devices and manages how data is stored on those devices - in charge of formatting disks - creates sectors and clusters - sends message when the disk is full or there is some other problem with writing data to the disk - virtual memory - CD-ROM, DVD-ROM - Flash drive 14 1. Manages and Interacts with Computer Hardware Provides the Interface for Input and Output Devices – keyboard, mouse, printer, – device drivers = software programs that allow the hardware device to be used by the operating system and by application software 15 2. Provides and Manages System Security Single-user Operating Systems minimal security user has full authority Multi-user Operating Systems login and password capability protection of user’s data stored on the server’s central hard disk drives protection and security for software programs 16 3. Provides the System Interface System Interface or shell = the interface between the user and the computer Command Line Interface (CLI) Linux, UNIX, DOS, older OS’s Graphical User Interface (GUI) 17 Command Line Interface 18 Windows 11 GUI 19 Macintosh 20 UNIX with X-Windows 21 4. Provides the Interface for Application Software Operating systems are designed and developed for a specific CPU or “family of CPUs” – Macintosh OS: Motorola 680xx, PowerPC Gx, Intel – DOS: Intel CPUs – Windows: Intel 80386, 80486, and Pentium CPUs – Linux: Intel CPUs – MS NT & 2000: Intel CPUs 22 4. Provides the Interface for Application Software Application software is developed for an operating system MS Word for Windows XP Windows XP Intel CPU MS Word for the Macintosh Macintosh OS X Gx CPU or Intel CPU 23 Compatibility Will software developed for one operating system work on another? Will MS Word for Macintosh run on a PC with Windows XP? Some software must be developed separately for each operating system. Special emulation software or hardware can be used to resolve compatibility issues. 24 Operating System Objectives Convenience – Makes the computer more convenient to use Efficiency – Allows computer system resources to be used in an efficient manner Ability to evolve – Permit effective development, testing, and introduction of new system functions without interfering with service 25 Components of an Operating System A common approach to OS development is to divide the systems into small components. Each component corresponds to the service the OS can provide. – Process Management – Main Memory Management – File Management – I/O System Management – Secondary Memory Management – Networking – Protection System – Command-Interpreter System 26 Basic OS Organization 27 System Design Goals User goals – the operating system should be convenient to use, easy to learn, reliable, safe, and fast. System goals – the operating system should be easy to design, implement, and maintain, as well as flexible, reliable, error-free, and efficient. 28 Types of Operating Systems Classification with respect to the type of computers they run on and the type of applications they support 1. Single-User, Single Task 2. Single-User, Multi-Tasking 3. Multi-User 4. Real-Time Operating System (RTOS) Types of Operating Systems Single user/Single tasking OS – One user works on the system – Performs one task at a time – MS-DOS and Palm OS – Take up little space on disk – Run on inexpensive computers Types of Operating Systems Single user/Multitasking OS ✓ User performs many tasks at once ✓ Most common form of OS ✓ Used by most all PC’s and Laptops ✓ Examples: Windows, Mac OS, Linux Types of Operating Systems Multi-user/Multitasking OS – Many users connect to one computer – Each user has a unique session – UNIX, Linux, and VMS – Maintenance can be easy – Requires a powerful computer Multi user/Multi tasking OS Real-time operating system – Very fast small OS – Built into a device – Respond quickly to user input – Examples: Real-time Linux, Real-time Windows NT Other Types of OS Mainframe operating systems Server operating systems Multiprocessor operating systems Personal computer operating systems Real-time operating systems Embedded operating systems Smart card operating systems Types of OS Types of OS History of Operating Systems It all started with computer hardware in about 1940s. ENIAC 1943 38 History of Operating Systems Computers were using vacuum tube technology. ENIAC’s vacuum tubes 39 History of Operating Systems ENIAC’s backside 40 History of Operating Systems Programs were loaded into memory manually using switches, punched cards, or paper tapes. ENIAC : coding by cable connections 41 History of Operating Systems punch card 42 History of Operating Systems Paper tape 43 History of Operating Systems As time went on, card readers, printers, and magnetic tape units were developed as additional hardware elements. Assemblers, loaders, and simple utility libraries were developed as software tools. 44 History of Operating Systems Finally, the idea of multiprogramming came. Multiprogramming means sharing of resources between more than one processes. By multiprogramming the CPU time is not wasted, because, while one process moves on some I/O work, the OS picks another process to execute till the current one passes to I/O operation. 45 History of Operating Systems With the development of interactive computation in the 1970s, time-sharing systems emerged. In these systems, multiple users have terminals (not computers) connected to the main computer and execute tasks on the main computer. 46 History of Operating Systems Main computer; having a CPU executing processes by utilization of the OS, (e.g. UNIX). Terminals are connected to the main computer and used for input and output. No processing is made. They do not have CPUs. 47 History of Operating Systems Distributed systems are similar to networks. However in such systems, there is no need to exchange information explicitly, it is handled by the OS itself whenever necessary. Each is a computer having its own CPU, RAM, etc. An OS supporting network is installed on 48 them. Today’s Operating Systems Multiple processors – Load balancing Dynamically allocating tasks to the various processors so that all processors are used efficiently. – Scaling Breaking tasks into a number of subtasks equal to the number of processors available. – The Network (Internet) Becoming a single network-wide operating system rather than a network of individual operating systems. 49 Why study Operating Systems? Build, modify, or administer an operating system Understand system performance – Behavior of OS impacts entire machine – Challenge to understand large, complex system – Tune workload performance – Apply knowledge across many areas Computer architecture, programming languages, data structures and algorithms, and performance modeling 50