Lecture 14: Operating Systems Intro to IT COSC1078 Introduction to Information Technology Lecture 14 Operating Systems James Harland

Lecture 14: Operating SystemsIntro to IT Introduction James Harland URL: Phone: Office: Consultation: Mon , Thu What colour is my office door? Carpet? Chair?

Lecture 14: Operating SystemsIntro to IT Introduction to IT 1 Introduction 2 Images 3 Audio 4 Video WebLearnTest 1 5 Binary Representation Assignment 1 6 Data Storage 7 Machine Processing 8 Operating Systems WebLearn Test 2 9 Processes Assignment 2 10 Internet 11 Internet Security WebLearn Test 3 12 Future of ITAssignment 3, Peer and Self Assessment

Lecture 14: Operating SystemsIntro to IT Overview  Questions?  Assignments 1 & 2  Operating Systems  Questions?

Lecture 14: Operating SystemsIntro to IT Assignments 1& 2 Assignment 1  Currently being marked  Will have marks out later this week Assignment 2  Specification has been published  Must be done in groups of 2 or 3  Can change groups from Assignment 1 (if you wish)  Must have a blog on Blackboard

Lecture 14: Operating Systems SE Fundamentals Questions? How did you spend 6-8 hours on this course last week? This week?

Lecture 14: Operating SystemsIntro to IT Operating Systems operating system kernel device driver open source real time virtual machine desktop publishing

Lecture 14: Operating SystemsIntro to IT Operating Systems Operating system

Lecture 14: Operating SystemsIntro to IT Operating Systems  Manage hardware and software resources  Memory allocation  Prioritising requests and processes  Controlling input and output devices  Managing network access  Managing file systems  Dealing with multiple users  …

Lecture 14: Operating SystemsIntro to IT Operating Systems HARDWARE USER

Lecture 14: Operating SystemsIntro to IT Operating Systems

Lecture 143: Operating SystemsIntro to IT Operating Systems  Concurrent execution of processes on a single CPU  Memory management Registers, caches, RAM, hard disk, plug-ins,... Movement of data between these  File systems  Networking  Printers, scanners, LAN, wireless, Internet,...

Lecture 14: Operating SystemsIntro to IT Operating Systems  Graphical User Interface (GUI) ‏ Colors, data, cursors,...  Device drivers Code specialised for particular hardware device (DVD writer, printer, monitor,...) ‏ Controls access to these  Security  Passwords, file sharing, protocols,...

Lecture 14: Operating SystemsIntro to IT Operating Systems  Desktop (Windows, MacOS, Linux,... ) ‏ Windows around 85% of market  Server systems Google “back end”, server farms,... Windows Server or Unix  Specialist systems  Supercomputers, call centres, real-time systems, PDA systems,...

Lecture 13: Operating SystemsIntro to IT Operating Systems

Lecture 14: Operating SystemsIntro to IT Linux  Open source  Developed in 1991 by Linus Torvalds  Written in C  RedHat, Mandrake, SUSE, Ubuntu,...  RedHat 7.1 has 30 million+ lines of code

Lecture 14: Operating SystemsIntro to IT Windows  Add-on to MS-DOS in 1985  Most popular OS  Known security issues  Windows XP 40 million lines of code  Vista released 2007  Windows 7 (now!)

Lecture 14: Operating SystemsIntro to IT MacOS  Only on Apples  Introduced by Apple in 1984  GUI from the start  Based on Unix  Graphics features  Mac OS X Leopard

Lecture 14: Operating SystemsIntro to IT Where to begin? How do you start an operating system? Boot it! (or bootstrap)  Turn on power ( )  Machine loads bootstrap program from ROM (non-volatile memory)  Bootstrap program loads OS  OS takes over

Lecture 14: Operating SystemsIntro to IT Initial State When Turned On Program Counter Instruction Register 00 ROM RAM ProcessorMemory Disk Bootstrap Program 00

Lecture 14: Operating SystemsIntro to IT Load Bootstrap Program Program Counter Instruction Register 00 ROM RAM ProcessorMemory Disk Bootstrap Program 00

Lecture 146: Operating SystemsIntro to IT Bootstrap program loads OS Program Counter Instruction Register 00 ROM RAM ProcessorMemory Disk Bootstrap Program 00

Lecture 14: Operating SystemsIntro to IT Bootstrap program loads OS Program Counter Instruction Register 00 ROM RAM ProcessorMemory Disk Bootstrap Program 00

Lecture 14: Operating SystemsIntro to IT Bootstrap program has loaded OS Program Counter Instruction Register AA ROM RAM ProcessorMemory Disk Bootstrap Program 00 AA

Lecture 14: Operating SystemsIntro to IT OS takes over execution Program Counter Instruction Register AA ROM RAM ProcessorMemory Disk Bootstrap Program 00 AA

Lecture 14: Operating SystemsIntro to IT Starting Up Operating Systems Program Counter Instruction Register AA ROM RAM ProcessorMemory Disk Bootstrap Program 00 AA

Lecture 14: Operating SystemsIntro to IT Starting Up Operating Systems Program Counter Instruction Register AA ROM RAM ProcessorMemory Disk Bootstrap Program 00 AA

Lecture 14: Operating SystemsIntro to IT Starting Up Operating Systems Program Counter Instruction Register AA ROM RAM ProcessorMemory Disk Bootstrap Program 00 AA

Lecture 16: Operating SystemsIntro to IT Multiple boot scenario … Program Counter Instruction Register 00 ROM RAM ProcessorMemory Disk Bootstrap Program 00

Lecture 16: Operating SystemsIntro to IT Multiple boot scenario … Program Counter Instruction Register 00 ROM RAM ProcessorMemory Disk Bootstrap Program 00

Lecture 16: Operating SystemsIntro to IT Multiple boot scenario … Program Counter Instruction Register 00 ROM RAM ProcessorMemory Disk Bootstrap Program 00

Lecture 14: Operating SystemsIntro to IT Multiple boot scenario … Program Counter Instruction Register 00 ROM RAM ProcessorMemory Disk Bootstrap Program 00

Lecture 14: Operating SystemsIntro to IT OS Software Classification Software SystemApplication Utility Kernel Operating System Shell

Lecture 16: Operating SystemsIntro to IT Processes

Lecture 14: Operating SystemsIntro to IT Processes A program is a static set of instructions A processes is the execution of a program, which changes state over time.

Lecture 14: Operating SystemsIntro to IT Processes Executing in Context Program Counter Instruction Register CC ROM RAM ProcessorMemory Disk 00 CC

Lecture 14: Operating SystemsIntro to IT Processes Executing in Context Program Counter Instruction Register DD ROM RAM ProcessorMemory Disk 00 CC DD

Lecture 14: Operating SystemsIntro to IT Processes Switching Ready Waiting Scheduler maintains process table

Lecture 14: Operating SystemsIntro to IT Processes Switching

Lecture 14: Operating SystemsIntro to IT Interrupts  Signals to the CPU  Often generated by timing circuits  CPU reacts by jumping to appropriate memory location  Dispatcher  selects a ready process  resets timing circuit  starts process  CPUs often designed to switch process states efficiently

Lecture 14: Operating SystemsIntro to IT Processes Executing in Context Program Counter Instruction Register BB ROM RAM Processor Memory Disk 00 BB

Lecture 14: Operating SystemsIntro to IT Processes Executing in Context Program Counter Instruction Register 11 ROM RAM Processor Memory Disk 00 BB

Lecture 14: Operating SystemsIntro to IT Processes Executing in Context Program Counter Instruction Register FF ROM RAM Processor Memory Disk 00 FF

Lecture 146: Operating SystemsIntro to IT Interrupts  Provide mechanism to switch processes  CPU doesn’t have to wait for I/O transfers  Switching leads to faster throughput  `Save document’ means CPU does something else while the save takes place

Lecture 15: Operating SystemsIntro to IT Conclusion  Work on Assignment 2  Web Quizzes and Web Test 2  Finish reading book!