ELET 4300 Lesson 01 Intro to Modern OS Fall 08292013

7/29/2019 ELET 4300 Lesson 01 Intro to Modern OS Fall 08292013

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LESSON 1 - 1ELET 4300

ELET4300UNIX Operating System

Lesson 1Introduction to Modern OS

Engineering TechnologyCollege of Technology

University of Houston


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Unit Objectives What is an operating system (OS)?

Computer System

Operating Systems How does an operating system differ from a computer program?

Computer System Architecture

General Purpose Digital Computer

Computer System Components Operating System Support Components

Operating System Goals

Why Study Operating Systems?

What Does a Modern Operating System Do?

Operating System Architecture

Interrupts, Interrupt Handling, and Interrupt Classes


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What is an Operating System (OS)?

Sometimes called the executive.

A software responsible for controlling theallocation and usage of hardware resources.

A program that acts as an intermediary between auser of a computer and the computer hardware.

Schedules computer hardware including the CPU,RAM, I/O, disks, etc.

Simplifies procedures for electronic mail, filetransfer, word-processing, etc.


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Banking

System

Web

Browser

Compilers EditorsCommand

Interpreter

Operating System

Microprograms

Physical Devices (Hardware)

Air line

Reservation

Machine Language

Application Programs

System Programs

Hardware

AComputer System

User


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Operating Systems

CPM

MS-DOS

Windows-95, 98, 2000, XP, NT, 2007

Unix

Linux

AIX Sun Solaris


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How Does an Operating SystemDiffer From a Computer Program?

The operating system is the host platform forthe compiler (e.g., C, C++, J ava, etc.).

The operating system can access allhardware devices associated with the system.

The operating system has extendedcapabilities (scheduling, I/O, file control, etc.).


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Computer SystemArchitecture

Central Processing Unit (CPU)

Random-Access Memory (RAM)

Read-Only Memory (ROM)

System and Disk Storage Devices

I/O interface (PIAs, Modems, NICs)

Peripherals (CD ROMs, DVDs, VGAs, Drivers)


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General PurposeDigital Computer

CPU

Data Bus

Address Bus

Control Bus

RAM I/O Interface

Registers ALU Control

Peripherals


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Computer System Components Hardware provides basic computing resources

(CPU, memory, I/O devices)

Operating System controls and coordinatesthe use of the hardware among the variousapplication programs for the various users

Application Programs define the ways inwhich the system resources are used to solvethe computing problems of the users (compilers,

database systems, video games, businessprograms)

Users (people, machines, other computers)


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Computer-System Operation

I/O devices and the CPU can executeconcurrently

Each device controller is in charge of aparticular device type and has a local buffer.

CPU moves data from/to main memory

to/fromlocal buffers I/O is from the device to local buffer of

controller

Device controller informs CPU that it hasfinished its operation by causing an interrupt


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Conceptual View of a

Computer System Operation

Processor . . .

.

.

.

I/O Controller

Processor

I/O Controller

I/O Controller

Memory

Operating

System

Software

Programs

and Data

Programs

I/O Devices

Data

OS

Storage

.

.

.


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Operating SystemSupport Components

File Manager

The BIOS (Basic Input/OutputSystem)

Device Drivers

Shells Memory Management


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File Manager DOS

FAT (File AllocationTable)Directory Structure

File Name Extensions (.BAT, .EXE, .SYS,

etc.) UNIX

Paths and directory structure

Unix directories (/bin, /usr, /tmp, etc.)File permissions (chgrp, chmod, chown)


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Shell User-interface to the operating system.

DOSSpecifies location of the DOS command interpreter;

sets environment space.

UNIXHighly developed (Bourne, C, Korn shells).

Supports programmable user interface.


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UNIX Developed from MULTICS - multi-user interactive

system supported by a GE-645 mainframe (1965-69)

Ken Thompson of AT&T Bell Labs developed thefirst UNIX operating system for a DEC PDP-7

UNIX never intended as a commercial product

1970s - Universities were encouraged to developand use the UNIX system

1980s - engineering and CAD applications

1990s - Server side of a client/server model


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Modern Operating System Goals Efficient Use of Resources

Avoid bottlenecks that affect performance. Keep all components as busy as possible.

Convenience and Productivity for Users

The user costs more than the machine. Deliver function as efficiently as possible.

Availability and Reliability

Computer systems are critical. A failed system can mean a failed company.


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What Does a Modern OS Do? Provides Abstraction

Clean interfaces to hardware

Processes

Unbounded Memory

Files

Synchronization and Communications

Provides Standard Interface Portability (Unix runs on many very different

computer systems)


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What Does a Modern OS Do? (Cont.)

Mediate Resource Usage

Allow multiple users to share resources fairly,efficiently, safely, and securely

Multiple Processes

Multiple Programs

Consumes Resources Takes up physical memory

CPU time


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Operating System

Architecture Most users see total

package: Windows,Unix

Tighter integration in

modern systems

Hardware

Operating System

Libraries Utilities

Interface


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Other Examples of Abstractions Threads or Processes (Fork)

Address Spaces (Allocate, Deallocate) Files (Open, Close, Read, Write)

Messages (Send, Receive)


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Interrupts Interrupt transfers control to the interrupt service

routine (ISR) generally, through the interrupt

vector, which contains the addresses of all theservice routines.

Interrupt architecture must save the address of

the interrupted instruction. Incoming interrupts are disabled while another

interrupt is being processed to prevent a lostinterrupt.

A trap is a software-generated interrupt causedeither by an error or a user request.

An operating systemis interrupt driven.


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Interrupt Handling The operating system preserves the state of the

CPU by storing registers and the programcounter. Determines which type of interrupt has occurred:

polling - generally a high-overhead operation

vectored interrupt system- more efficient Separate segments of code determine what action

should be taken for each type of interrupt.


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Interrupt Classes

Supervisor Interrupts Initiated by a running process that executes the

supervisory call instruction.

Include user request for a particular service:

Performing I/O Obtaining more storage

I/O Interrupts

Initiated by I/O hardware and are caused when anI/O operation completes, when an I/O error occurs,or when an I/O device is made ready.


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Interrupt Classes (Cont.)

External InterruptsInitiated by operator, receipt of signal from another

processor on a multiprocessor system.

Restart InterruptsInitiated by consoles restart button, or restartinstruction arrives from another processor on amultiprocessor system.


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Interrupt Classes (Cont.)

ProgramCheck Interrupts Initiated by programs machine language instructions.

Include division by zero,

arithmetic overflow or underflow,

data is in the wrong format,

attempt to execute an invalid operation code, attempt to reference a memory location beyond the limits of real

memory,

attemptby a user process to execute a privileged instruction,

and an attempt to reference a protected resource.

Machine Check Interrupts Initiated bymalfunctioning hardware.


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Low-Level & High-Level Codes

Machine code Assembly code (x86 processors)0100 BA0901 MOV DX,0109H

0103 B409 MOV AH,09H

0105 CD21 INT 21H

0107 CD20 INT 20H0109 54 45 53 54 24 0109 DB TEST$

Shell Script (csh)% echo TEST

/* C code */ // C++ code#include #include

#include using namespace std;

int main(void) int main(void)

{ {

printf(TEST); cout


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1981 1999 factorCPU (MHz) 10 550 55

DRAM Capacity 128 KB 128 MB 1000

Disk capacity 10 MB 16GB 1600

Net Bandwidth 9600 b/s 155 Mb/s 16000

#address bit 16 64 4

Cycles/instruction 3-4 0.5-1 3-8

History of Operating Systems:

Change!Typical academic computer in 1981 and 1999

Operating systems have to vary over time to

adapt to changing tradeoffs.


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References1. Operating Systems: Internals and Design PrinciplesWilliam StallingsPrentice Hall; 7th edition (J uly 28, 2011)

2. Operating Systems: Design and ImplementationAndrew S. Tanenbaum, Albert S. WoodhullPrentice Hall; 3rd edition (J une 15, 2011)

3. Computer Organization and Architecture: Designing for PerformanceWilliam StallingsPearson Education; International ed of 9th revised edition (May 1, 2012)

4. Operating System ConceptsAbraham Silberschatz, Peter Baer Galvin, Greg GagneWiley; 8th edition (December 1, 2011)

Documents

ELET 4300 Lesson 01 Intro to Modern OS Fall 08292013