OPERATING SYSTEM LESSON 1 - 3 Reviewer .docx

**OPERATING SYSTEM** **LESSON 1:** **What is an Operating System?** - **Computer System** = Hardware + Software - **Software** = Application Software + System Software (OS) **OPERATING SYSTEM** - the **primary software installed on a computer** that manages all the hardware and other softwa...

**OPERATING SYSTEM** **LESSON 1:** **What is an Operating System?** - **Computer System** = Hardware + Software - **Software** = Application Software + System Software (OS) **OPERATING SYSTEM** - the **primary software installed on a computer** that manages all the hardware and other software on a computer. - is **also a [software]** that [communicates with the **hardware**] and allows the running of other programs. - It consists of system software, or the basic files that your computer needs to boot and work. - Is a system software that acts as an **[intermediary/interface]** between a **[user of a computer]** and **[the computer hardware]**. - OS is a **[resource allocator]** - Manages all resources - Decides between conflicting requests for efficient and fair resource use. - OS is a **[control program]** - Controls execution of programs to prevent errors and improper use of the computer. **OPERATING SYSTEM GOALS:** 1. Execute user programs and make solving user problems easier. 2. Make the computer system convenient to use. 3. Use the computer hardware in an efficient manner. **FUNCTIONS OF OPERATING SYSTEM** 1. **PROCESS MANAGEMENT** **PROCESS** - is a **[program in execution]**. - needs certain resources, including **[CPU time]**, **[memory]**, **[files]**, and **[I/O devices]** to accomplish its task. - **DEPENDENT** -- they may try to **[share same resources]**, thus [task of process synchronization] comes to the picture. - **INDEPENDENT** -- a **[due care needs]** to be taken [to avoid their overlapping in memory] area. Based on priority, it is important to allow more important processes to execute first than others. 2. **MEMORY MANAGEMENT** **MEMORY** -- is a **[large array of words]** or **bytes**, each with its own address. - It is a repository of quickly accessible data shared by the CPU and I/O devices. **MAIN MEMORY** -- is a **[volatile storage device]**. - When the computer made turn off everything stored in RAM will be erased automatically. **VIRTUAL MEMORY SYSTEM** -- In addition to the physical RAM installed in your computer, most modern operating systems allow your computer to use a ***[virtual memory system]**.* **VIRTUAL MEMORY** -- allows your computer to **[use part of a permanent storage device (hard disk) as extra memory.]** The operating system is responsible for the following activities in connections with memory management: - Keep track of which parts of memory are currently being used and by whom. 3. **FILE MANAGEMENT** **FILE** -- is a **[collection of related information]** defined by its creator. **FILE SYSTEMS** -- provide the conventions for the **[encoding]**, **[storage]** and **[management of data]** on a storage device such as a [hard disk.] The operating system is responsible for the following activities in connections with file management: ✦ File creation and deletion. ✦ Directory creation and deletion. ✦ Support of primitives for manipulating files and directories. ✦ Mapping files onto secondary storage. ✦ File backup on stable (nonvolatile) storage media. 4. **DEVICE MANAGEMENT OR I/O MANAGEMENT** **DEVICE CONTROLLERS** -- are **[components on the motherboard]** / on expansion cards that [act as an interface between CPU] and [the actual device.] **DEVICE DRIVERS** -- are **[the OS software components]** that interact with the devices controllers. **INTERRUPT CONTROLLER** -- a **[special device inside CPU]** handles the task of [receiving interrupt requests] and prioritizes them to be forwarded to the processor. - Keeps tracks of all devices connected to system. - Designates a program responsible for every device known as Input/output controller. - Decides which process gets access to a certain device and for how long. - Allocates devices in an effective and efficient way - Deallocates devices when they are no longer required. 5. **SECURITY AND PROTECTION** - The OS [uses password protection to protect user data] and similar other techniques. - It also [prevents unauthorized access to programs and user data] by assigning access right permission to files and directories. - The owners of information stored in a multiuser or networked computer system may want to control use of that information, concurrent processes should not interfere with each other. 6. **CONTROL OVER SYSTEM PERFORMANCE** - [Recording delays between request for a device for a service] and [response from the system. ] - The operating system [monitors the overall health of the system] in order to optimize performance. - To get a thorough picture of the system's health, keep track of the time between system responses and service requests. - This [can aid performance by providing critical information for troubleshooting issues.] 7. **JOB ACCOUNTING** - Keeping track of time and resources used by various job and users. - The OS **[maintains track]** of [how much time and resources are consumed by different tasks and users,] and this data can be used to measure **[resource utilization]** for a specific user or group of users. 8. **ERROR DETECTING AIDS** - The OS constantly **[monitors the system]** in order [to discover faults] and [prevent a computer system from failing.] 9. **COORDINATION BETWEEN OTHER SOFTWARE AND USERS** - [Coordination and assignment of compilers, interpreters, assemblers], and other software to the various users of the computer systems. **LESSON 2: HISTORY OF OPERATING SYSTEM** **FIRST TRUE DIGITAL COMPUTER** -- was designed by [English Mathematician] **[Charles Babbage]**. **COMPUTER** -- had a **[Mechanical Design]**, It was slow and unreliable and they are known as ―**[Analytical Engine‖.]** **1940** -- **[First electronic computers were introduced.]** - These electronic computers were [made without any Operating Systems.] - All programming was [done in absolute machine language] often by wiring up [plug boards] to control the machine's basic functions. 1. **FIRST GENERATION (1945 -- 1955)** - Technology has been used as a **[vacuum tubes]** and **[OS was not present]** and the [language was a machine language] which is called [binary language]. 2. **SECOND GENERATION (1955 -- 1965)** - **technology was [transistors]**, [operating system is present], and the language was used **[assembly]** and **[high level language.]** - **1950** -- **[General Motors]** [created the first OS]. - It was called **[GMOs]** and is **[used to run single IBM]** (International Business Machines) mainframe computers. - First the programmers would [construct a program on a piece of paper.] The [program will then be **punched on cards**] and will be brought to the operator. - Using this new system, the data accumulated was submitted into groups and thus they were called **[single-stream batch processing systems.]** - **1955** -- **[transistors were introduced]** and **[first OS]** **[was FORTRAN Monitor System]** was introduce in a computers, and also [FORTRAN is a high level language] was used. - The working of batch system **[in second generation were all magnetic]** tapes are mounted on a tape drive; operator load special program which read the first job from the tape and run it. - **[Output was written unto the second tape]**, after each job finished, the OS automatically read next job from the tape and output tape inserted into **[IBM 1401 for printing.]** - The features on second generation computers are computers used transistors as their main electronic component. - Some [high level languages] of this generation are **[COBOL]** and **[FORTAN]** were introduced towards the end of second generation. 3. **THIRD GENERATION (1965 -- 1980)** **Late 1960's** -- OS designers were **[able to develop the system of multiprogramming]** in which a computer program will be able to perform multiple jobs at the same time. - In the same year, the [**first version of the UNIX** operating system was created. ] - The PDP-1 had only 4K of 18-bit words, but at \$120,000 per machine (less than 5 percent of the price of a 7094), it sold like hotcakes. - **1961** -- [phenomenal growth of mini computer starting with the DEC PDP -- 1.] The PDP-1 had only 4K of 18-bit words, but at \$120,000 per machine (less than 5 percent of the price of a 7094), it sold like hotcakes. - were technology was **[integrated circuits]**, [operating system was present] and the [language was used is **high level language.**] [ ] - In this generation computers are **[based on Integrated Circuits]** and was [invented by] **[Robert Noyce]** and **[Jack Kilby]** in **1958-1959.** - **INTEGRATED CIRCUITS** - are **[single component]** containing **[number of transistors.]** Few examples of this are PDP-8, PDP-11, ICL 2900,IBM 360,IBM 370 and many more. 4. **FOURTH GENERATION (1980 -- Present Day)** **STEVE JOBS** - **[co-inventor of Apple computer]**, **[adapted GUI]** and **[Apple Macintosh]** became a **[huge success]** not only because it is cheaper but with the [adaption of GUI] it is [user-friendly]. **Mid 1980s** -- there where growths of network operating systems and distributed operating systems being used in every personal computer. - Today, numerous types of operating system are being used in different types of machines. **LESSON 3: TYPES OF OPERATING SYSTEM** TYPES OF OS 1. **BATCH OPERATING SYSTEM** -- The users of this type of operating system **[does not interact with the computer directly.]** - Each user prepares his job on an off-line device like punch cards and submits it to the computer operator - There is an operator which takes similar jobs having the same requirement and group them into batches. **ADVANTAGES OF BATCH OS:** - Processors of the batch systems know how long the job would be when it is in queue - Multiple users can share the batch systems - The idle time for the batch system is very less - It is easy to manage large work repeatedly in batch systems **DISADVANTAGES OF BATCH OPERATING SYSTEM:** - The computer operators should be well known with batch systems - Batch systems are hard to debug - It is sometimes costly - The other jobs will have to wait for an unknown time if any job fails **Examples of Batch OS:** - IBM's MVS 2. **MULTIPROGRAMMING OS --** This type of OS is **[used to execute more than one jobs simultaneously by a single processor]**. - [It increases CPU] utilization by organizing jobs so that the CPU [always has one job to execute.] - Multiprogramming operating systems **[use the mechanism of job scheduling]** and **[CPU scheduling]**. 3. **TIME-SHARING OS -- [Each task is given some time to execute]** so that all the **[tasks work smoothly]**. - Also known as **[Multitasking Systems]** - The **task** can be from a **[single user]** or **[different users]** also. - **QUANTUM** -- The **[time that each task gets to execute.]** - After this time interval is over OS switches over to the next task. 4. **MULTIPROCESSOR OS --** also known as **"[Parallel OS"] or "[Tight coupled OS."]** - have **[more than one processor]** in close communication that **[sharing the computer bus]**, **[the clock]** and sometimes **[memory]** and **[peripheral devices]**. - It **[executes multiple jobs]** at the [same time] and makes the processing [faster]. - It **[supports large physical address space]** and **[larger virtual address space.]** - If [one processor fails] then other processor [should retrieve] the interrupted process state so execution of process can continue. - Inter-processes communication mechanism is provided and implemented in hardware. 5. **DISTRIBUTED OS -- [Independent systems]** possess their own **[memory unit]** and **[CPU.]** - Referred to as **[LOOSELY COUPLE SYSTEM]** - Various autonomous interconnected computers communicate with each other using a shared communication network. Example: - Locus - DYSEAC 6. **NETWORK OS --** These **[manage data]**, **[users]**, **[groups]**, **[security]**, **[applications]**, and other networking functions. - **[Allow shared access of files]**, **[printers]**, **[security]**, **[applications]**, and other networking functions over a small private network**.** - **[CLIENT COMPUTERS]** -- The "other" computers arc called Client computers, and each computer that connects to a network server must be running client software designed to request a specific service. - popularly known as **["tightly coupled systems."]** **ADVANTAGES OF NETWORK OS:** - Highly stable centralized servers - Security concerns are handled through servers - New technologies and hardware up-gradation are easily integrated into the system - Server access is possible remotely from different locations and types of systems **DISADVANTAGES OF NETWORK OS:** - Servers are costly - User has to depend on a central location for most operations - Maintenance and updates are required regularly **Examples of Network Operating System are:** - Microsoft Windows Server 2003/2008/2012 - UNIX - Linux - Mac OS X - Novell NetWare - BSD, etc. 7. **REAL-TIME OS --** These types of Oss **[serve real-time systems.]** - This **time interval** is called **["response time."]** - **REAL-TIME SYSTEMS** [ --] used when there are **[time requirements ]** - missile systems, - air traffic control systems, - robots, etc. 8. **EMBEDDED OS --** An embedded os is one that **[is into the circuitry of an electronic device.]** - Embedded operating systems are now found in automobiles, bar-code scanners, cell phones, medical equipment, and personal digital assistants. - The most popular embedded operating systems for consumer products, such as PDAs, include the following: - Windows XP Embedded - **Windows CE.NET**: - it **[supports wireless communications]**, **[multimedia]** and **[Web browsing]**. It also [allows for the use of smaller versions of Microsoft Word], [Excel], and [Outlook]. - **Palm OS**: - It is **[the standard operating system for Palm-brand PDAs]** as well as other proprietary handheld devices. - **Symbian**: - OS **found in " smart" cell phones from [Nokia]** and **[Sony Ericsson]** 1. **DESKTOP CLASS OS** - Windows - OS X - UNIX/LINUX - Chrome OS - Windows Server - Mac OS X Server - UNIX/LINUX **DESKTOP CLASS OS:** PLATFORM: the hardware required to run a particular OS - **INTEL PLATFORM (IBM -- COMPATIBLE)** - Windows - DOS - UNIX - LINUX - **MACINTOSH PLATFORM** - Mac OS - **IPAD AND IPHONE PLATFORM** - IOS 1. **MS -- DOS** -- **[Single User Single Tasking OS]** - It **[had no built-in support for networking]**, and **[users had to manually install drivers]** any time they added a new hardware component to their PC. - DOS **supports only [16-bit programs]**[.] - [Command line user interface]. So, why is DOS still in use? - Two reasons are its size and simplicity. It does not require much memory or storage space for the system, and it docs not require a powerful computer. 2. **MICROSOFT WINDOWS** -- The graphical MS OS **[designed for Intel platform desktop]** and **[notebook computers]**. - Best known, [greatest selection of applications] available. - Current editions include **[Windows 7, 8, 8.1 and 10.]** 3. **MAC OS** -- User-friendly, runs on Mac hardware. Many applications available. - Current editions: [Sierra], [High Sierra], [Mojave], [Catalina] & [Big Sur]---Version XI(Released in Nov 2020) 4. **LINUX** -- an open-source, cross-platform OS that runs on desktops, notebooks, tablets, and smartphones. - The name Linux is a **combination [Linus]** (the first name of the first developer) and **[UNIX]** (another operating system. - Users are **[free to modify the code]**, **[improve it]**, and **[redistribute it]**, - Developers are **[not allowed to charge money for the Linux kernel]** itself (the main part of the operating system), but they can charge money for distributions (distros for short). 5. **GOOGLE CHROME OS** - **CHROME OS --** Is a **[popular thin client OS]**. - **THIN CLIENT --** A **[computer with minimal hardware]**, designed for a specific task. For example, a thin web client is designed for using the Internet. **SERVER OS:** 1. **WINDOWS SERVER** -- Familiar GUI interface for those experiences with Windows. 2. **UNIX** -- Very mature server capabilities, time-tested, large user community, stable 3. **LINUX** -- Free, customizable, many free services and utilities available. 4. **TABLET AND PHONE OS** - **SYSTEM-ON-CHIP (SoC**) -- An **[OS that comes preinstalled on a chip on a portable device]** such as a [smartphone.] - **POPULAR SoC OS:** - IOS: for Ipad, Iphone - Android: for a variety of tablets and phones - **DOWNLOADABLE APPLICATIONS** (APPS) FROM AN APP STORE, for example: - Apple App Store - Google Play Store 5. **IOS ON THE IPHONE AND** **IPAD** -- The **[Apple created OS for Apple and phones]**. - The [current stable version], **[IOS 14]**, was [released] to the public on **[September 16, 2020.]** 6. **ANDROID** -- a **[popular OS for smartphones and tablets]**, **is based on [Linux Kernel.]** - **[Developed by Google]** - Current versions include: [Android 8 Oreo], [Android 9 Pie], [Android 10], [Android 11] (released on September 2020)