Computer and Computer and Information ScienceInformation Science

Computer Computer SoftwareSoftware Computer Computer SoftwareSoftwareChapter 1.2Chapter 1.2

AgendaAgendaAgendaAgenda Application SoftwareApplication Software Operating SystemsOperating Systems

SoftwareSoftwareSoftwareSoftware SoftwareSoftware is the is the programsprograms and and datadata that that

a computer uses.a computer uses. Programs are lists of instructions for Programs are lists of instructions for

the processor.the processor. Data can be any information that a Data can be any information that a

program needs: character data, program needs: character data, numerical data, image data, audio numerical data, image data, audio data, and countless other types.data, and countless other types.– Digitizing :Digitizing :The process of taking a visual image, or

audio recording and converting it to a binary form for the computer.

Types of ProgramsTypes of ProgramsTypes of ProgramsTypes of Programs Imagine that you have just turned Imagine that you have just turned

on your computer and have not yet on your computer and have not yet started any application. Are any started any application. Are any programs running? programs running?

Two types of softwareTwo types of software– Application softwareApplication software– System software/Operating systemsSystem software/Operating systems

Why do we need an OS?Why do we need an OS? What are the goals of an Operating

System?– The primary goal of an Operating System is

to make the computer system convenient to use.

– The secondary goal is to make the computer system efficient to use.

An Operating SystemAn Operating System It underlies all other software. It acts as an interface between a user of a acts as an interface between a user of a

computer and the computer hardwarecomputer and the computer hardware ItIt manages and coordinates computer manages and coordinates computer

system resources ( CPU, memory, file system resources ( CPU, memory, file system, I/O devices)system, I/O devices)

It provides the user Interface that is:– How can something as simple-minded as a processor and

memory present you with something as rich as the Mac or Windows GUI?

Operating system services ...

Control basic input and output

Allocate system resources

Manage storage space

Operating Systems

Detect equipment failure

Maintain security

Operating system services ...

• You ask MS Word to OPEN a document– File menu/Open…

– WHAT WILL YOU SEE?

– What really just happened in the box?

WORD called on WORD called on O.S.O.S. to present to present you with that file list!you with that file list!O.S. must look at:O.S. must look at:1.1. Disk Directory (list of Disk Directory (list of filenamesfilenames))2.2. File Allocation Table (File Allocation Table (FATFAT)…. )….

(list of file (list of file locations: starting locations: starting position/cluster number on the disk)position/cluster number on the disk)

System calls

Multi-taskingMulti-tasking >1 program or person can share

computer resources. – CPU is idle ~90% of time, waiting for user input !

– One program active; Others running in the background

OS must protect each program’s memory area to ensure that instructions and data don’t “leak” into an area allocated to another program. If it fails, programs can crash…more shortly!

Booting and BIOSBooting and BIOSBooting and BIOSBooting and BIOS When a computer is started up, the When a computer is started up, the

hardware will automatically load the hardware will automatically load the operating system and start it running. This operating system and start it running. This process is called process is called bootingbooting..

BIOS is the boot program on a computer, BIOS is the boot program on a computer, and controls the computer from the time and controls the computer from the time you start it up until the operating system you start it up until the operating system takes over. When you turn on a PC, the takes over. When you turn on a PC, the BIOS first conducts a basic hardware BIOS first conducts a basic hardware check, called a Power-On Self Test (POST), check, called a Power-On Self Test (POST), to determine whether all of input/output to determine whether all of input/output devices are present and working. Then it devices are present and working. Then it loads the operating system into your loads the operating system into your computer's RAM.computer's RAM.

ROM (Read-only-Memory)ROM (Read-only-Memory)ROM (Read-only-Memory)ROM (Read-only-Memory) ROM refers to computer memory ROM refers to computer memory

chips containing permanent or chips containing permanent or semi-permanent data. Unlike RAM, semi-permanent data. Unlike RAM, ROM is non-volatile; even after you ROM is non-volatile; even after you turn off your computer, the turn off your computer, the contents of ROM will remain . contents of ROM will remain .

BIOS is stored in a ROM. BIOS is stored in a ROM.

Various Operating SystemsVarious Operating Systems Windows : Developed by Microsoft

XP, Vista, windows7 Unix: Developed by AT&T for large

companies Linux: Open Source version of

Unix Mac OS: only for Mac hardware

e.g. Snow Leopard

UNIX

SunOS UNIX

login: smithPassword:Last login: Oct 15 17:42:09 from tserv1.edu

SunOS Release 4.1.1 #1: Wed Mar 20 11:24:14 AST 1991

You have mail.

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UNIX features a command line interface. Designed for minicomputers but is now also available for micros and mainframes.

UNIX features a command line interface. Designed for minicomputers but is now also available for micros and mainframes.

The UNIX prompt

Microcomputer Operating Systems

Why is it important for me to know which operating system is on my computer?

IMPORTANT !

WHAT HAPPENS when you SHUT DOWN improperly? Why should you care?

““Shutting down incorrectly is a little like Shutting down incorrectly is a little like stopping your car by driving it into a wall. stopping your car by driving it into a wall. It works, but it can cause some damage.”It works, but it can cause some damage.”

Computer terms bingoComputer terms bingoComputer terms bingoComputer terms bingo Follow the link Follow the link http://www.wcu.edu/ceap/Kirk/Merlot_Resources/KnowYourComputerTerms.swf