Lecture 14: Operating Systems Intro to IT

COSC1078 Introduction to Information Technology

Lecture 14

Operating SystemsJames Harland

james.harland@rmit.edu.au

Lecture 14: Operating Systems Intro to IT

Introduction

James Harland• Email: james.harland@rmit.edu.au• URL: www.cs.rmit.edu.au/~jah• Phone: 9925 2045• Office: 14.10.1 • Consultation: Mon 4.30-5.30, • Thu 11.30-12.30What colour is my office

door? Carpet? Chair?

Lecture 14: Operating Systems Intro to IT

Introduction to IT1 Introduction 2 Images3 Audio4 Video WebLearnTest 1 5 Binary Representation Assignment 16 Data Storage7 Machine Processing8 Operating Systems WebLearn Test 29 Processes Assignment 210 Internet11 Internet Security   WebLearn Test 312 Future of IT Assignment 3, Peer and Self Assessment

Lecture 14: Operating Systems Intro to IT

Overview Questions?

Assignments 1 & 2

Operating Systems

Questions?

Lecture 14: Operating Systems Intro 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 Systems Intro to IT

Operating Systems

operating system

kernel device driver

open source real time

virtual machine

desktop publishing

Lecture 14: Operating Systems Intro to IT

Operating Systems

Operating system

Lecture 14: Operating Systems Intro 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 Systems Intro to IT

Operating Systems

HARDWAREHARDWARE

USER

Lecture 14: Operating Systems Intro to IT

Operating Systems

Lecture 143: Operating Systems Intro 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 Systems Intro 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 Systems Intro 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 Systems Intro to IT

Operating Systems

Lecture 14: Operating Systems Intro to IT

Linux Open source Developed in 1991 by Linus Torvalds Written in C RedHat, Mandrake, SUSE, Ubuntu, ... RedHat 7.1 has30 million+ lines of code

Lecture 14: Operating Systems Intro to IT

Windows Add-on to MS-DOSin 1985 Most popular OS Known securityissues Windows XP 40 million lines of code Vista released 2007 Windows 7 (now!)

Lecture 14: Operating Systems Intro 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 Systems Intro 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 Systems Intro to IT

Initial State When Turned On

Program Counter

InstructionRegister

00 ROM

RAM

Processor Memory Disk

BootstrapProgram

00

Lecture 14: Operating Systems Intro to IT

Load Bootstrap Program

Program Counter

InstructionRegister

00 ROM

RAM

Processor Memory Disk

BootstrapProgram

00

Lecture 146: Operating Systems Intro to IT

Bootstrap program loads OS

Program Counter

InstructionRegister

00 ROM

RAM

Processor Memory Disk

BootstrapProgram

00

Lecture 14: Operating Systems Intro to IT

Bootstrap program loads OS

Program Counter

InstructionRegister

00 ROM

RAM

Processor Memory Disk

BootstrapProgram

00

Lecture 14: Operating Systems Intro to IT

Bootstrap program has loaded OS

Program Counter

InstructionRegister

AA ROM

RAM

Processor Memory Disk

BootstrapProgram

00

AA

Lecture 14: Operating Systems Intro to IT

OS takes over execution

Program Counter

InstructionRegister

AA ROM

RAM

Processor Memory Disk

BootstrapProgram

00

AA

Lecture 14: Operating Systems Intro to IT

Starting Up Operating Systems

Program Counter

InstructionRegister

AA ROM

RAM

Processor Memory Disk

BootstrapProgram

00

AA

Lecture 14: Operating Systems Intro to IT

Starting Up Operating Systems

Program Counter

InstructionRegister

AA ROM

RAM

Processor Memory Disk

BootstrapProgram

00

AA

Lecture 14: Operating Systems Intro to IT

Starting Up Operating Systems

Program Counter

InstructionRegister

AA ROM

RAM

Processor Memory Disk

BootstrapProgram

00

AA

Lecture 16: Operating Systems Intro to IT

Multiple boot scenario …

Program Counter

InstructionRegister

00 ROM

RAM

Processor Memory Disk

BootstrapProgram

00

Lecture 16: Operating Systems Intro to IT

Multiple boot scenario …

Program Counter

InstructionRegister

00 ROM

RAM

Processor Memory Disk

BootstrapProgram

00

Lecture 16: Operating Systems Intro to IT

Multiple boot scenario …

Program Counter

InstructionRegister

00 ROM

RAM

Processor Memory Disk

BootstrapProgram

00

Lecture 14: Operating Systems Intro to IT

Multiple boot scenario …

Program Counter

InstructionRegister

00 ROM

RAM

Processor Memory Disk

BootstrapProgram

00

Lecture 14: Operating Systems Intro to IT

OS Software Classification

Software

SystemApplication

Utility

Kernel

Operating System

Shell

Lecture 16: Operating Systems Intro to IT

Processes

Lecture 14: Operating Systems Intro 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 Systems Intro to IT

Processes Executing in Context

Program Counter

InstructionRegister

CC ROM

RAM

Processor Memory Disk

00

CC

Lecture 14: Operating Systems Intro to IT

Processes Executing in Context

Program Counter

InstructionRegister

DD ROM

RAM

Processor Memory Disk

00

CC

DD

Lecture 14: Operating Systems Intro to IT

Processes Switching

Ready

Ready

Waiting

Scheduler maintains process table

Lecture 14: Operating Systems Intro to IT

Processes Switching

Lecture 14: Operating Systems Intro 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 Systems Intro to IT

Processes Executing in Context

Program Counter

InstructionRegister

BB ROMRAM

Processor Memory Disk00

BB

Lecture 14: Operating Systems Intro to IT

Processes Executing in Context

Program Counter

InstructionRegister

11 ROMRAM

Processor Memory Disk00

BB

Lecture 14: Operating Systems Intro to IT

Processes Executing in Context

Program Counter

InstructionRegister

FF ROMRAM

Processor Memory Disk00

FF

Lecture 146: Operating Systems Intro 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 Systems Intro to IT

Conclusion

Work on Assignment 2

Web Quizzes and Web Test 2

Finish reading book!