Chapter 3 – Systems Software

1) Overview

a) Systems vs Application software

i) Systems software? – for computer - control its internal functioning

ii) Applications software? – end user needs – Chapter 5

b) Categories of systems software

i) operating system

ii) system utilities

2) Operating system

a) Differs by type of computer and platform

i) Type – micro vs mainframe (Windows vs MVS)

ii) Micro platforms? PC vs Mac (Win vs MacOS)

b) General functions

i) Communication with the user (aka user interface) – eg; launch programs, print, save

ii) Managing System Resources – CPU and Memory – ‘P’ in the IPOS fundamental operations

iii) Manages the hardware – eg: storage/retrieval from disk, input from keyboard, monitor display

iv) Interacting with software

(1) Application programs (eg: Word) make various requests

(a) Print a document, open a file, save a file

(2) OS must respond to these requests

3) User interface (aka shell)

a) Purpose system software? – for computer to control its internal functioning

i) Small OS part for you –  User interface interacts with user

b) types

i) graphical, command line

c) graphical user interface – GUI – most common - characterized by

i) desktop – appears after OS is loaded

(1) can customize via Control Panel/Appearance and Personalization

ii) click icons

(1) initiate commands (print) and launch programs (MS Word)

iii) sizeable windows (lab)

(1) how? Maximize button, minimize button, click and hold Title Bar, click and hold on window edges

iv) pull down menus – File/Edit/View

v) dialog boxes – provide additional info

(1) print dialog box

d) command line – text only

i) type keywords

ii) Copy command example

(1) exact syntax required

(a) Copy c:\yourfile.txt f:\myfile.txt

(2) what does that statement do?

(a) Copies file from hard disk (C: drive) to jump drive (F:)

iii) DOS

e) Pictures 70 - 74 – evolution of MS operating system user interface

i) DOS thru Windows 10

4) Managing System Resources – CPU and Memory

a) Processing

i) Single-tasking OS

(1) Older OS’s

(2) Can run only one application at a time

ii) multitasking

(1) CPU capable of switching between multiple programs

(2) doesn’t actually run 2 programs at once – speed of switching makes it appear that way

b) Managing Memory – multiple programs in memory

i) partitions

(1) multitasking programs - shares memory – no overwriting

(2) each gets own partition

(3) Windows 3.1 – GPF – memory management error by OS

c) View/Cancelling executing processes

i) Task Manager

(1) Access via right click taskbar > Task Manager

(2) Cancel task “not responding”

(a) work not lost in other programs

d) Buffering

i) Operating system holds commands until resources are available to execute them

(1) Eg: command given to print 3 documents

(a) 1 document prints

(b) 2 held in print buffer (aka print queue) until printer is available (pic page 76)

ii) Spooling program (aka spooler) monitors the buffer and releases the next task when the device (in this case the printer) is available

e) virtual memory – illusion that you have additional memory 

i) if RAM is full – swap file (aka paging file) on the hard disk used

ii) data/programs divided into pages

iii) pages swapped as needed

iv) swapping (aka paging) slows performance

(1) close excess applications (on task bar) to improve performance

v) Windows Vista and Windows 7 introduced a ReadyBoost feature

(1) Use Flash Drive for Virtual memory – better performance the hard disk

5) Managing and Controlling Hardware

a) OS controls communication with hardware

i) Device drivers and interrupts - Tell OS how and when to talk to hardware

b) Device drivers

i) tell OS how to talk to hardware

ii) when computer turned on – boot process occurs

(1) OS system performs Power On Set Test – POST

(2) Determines if hardware devices are working

(3) OS examines device drivers - determines how to communicate with hardware

iii) When you add hardware

(1) OS examines device driver – determines how to communicate with it

(2) Plug and Play (PnP) – Win 95 innovation

iv) Source

(1) popular peripheral brands – included with OS

(2) new brands (after release of OS) device driver provided on CD or downloaded

v) Device driver problems – must uninstall device driver

(1) Able to boot – uninstall via Device Manager

(2) Unable to boot – boot in Safe Mode – boots with limited devices - then uninstall

c) Interrupts – sent by peripheral to OS

i) Interrupts tell OS when to talk with peripherals

(1) keyboard - key pressed

(2) disk – data retrieved

6) Interacting with software

a) App Software must interact with OS

i) Concept diagram handout

ii) Example handout

iii) Only buy Apps for OS its designed for – Win or Mac

b) App Software (eg: Word) requests services from OS via Application Programming Interface (API)

i) Word requests Win to print/save – done via API – pic page 79

c) Control of OS – gives application edge

i) Microsoft antitrust suit

7) Specific Desktop OS’s

a) Desktop OS – OS for micro computers – PC or MAC

b) Majority are MS Windows, MAC OS X or Linux

c) Other Computers types (eg: mainframes, supercomputers) different OSs

8) Window OS

a) DOS - Pre-Windows

i) on IBM PC 1981 – launched MicroSoft

ii) command line interface

(1) problem with command line interface?

(2) Text only, exact syntax required

iii) real mode only

(1) no memory partitions

(2) implies? no multitasking

b) Windows 3.X

i) X – versions 3.0, 3.1 etc – early 90’s

ii) 1^st widely used GUI on IBM compatibles

(1) Win 1.0 and 2.0 preceded this – but with minimal marketplace impact

iii) protected mode capabilities

(1) partitions

(2) implies? Multitasking

iv) General Protection Faults (GPF’s) common problem

c) Win 95

i) Introduced Plug and Play (PnP) – OS automatically determines how to communicate with new hardware

d) Win 98

i) Start Button

ii) Same GUI as 95

iii) better Internet connectivity

iv) more device drivers – DVD-ROM

e) Win XP ( 2001)

i) Automatic updates – previously updating OS difficult and often damaging

(1) MAC commercial – PC on hospital gurney for upgrade

(2) Win XP more reliable

ii) First GUI change since Win 95

f) Windows Vista (2007)

i) Focuses on ease of use and multimedia

(1) Thumbnails – hover mouse over taskbar items – miniature view of screen

(2) Gadgets – sidebar items – weather, calendar

(3) Windows Messenger – IM

(4) Windows DVD maker – burn DVD

ii) Windows Defender – enhanced security – criticism of Win XP and earlier versions

g) Windows 7 (2009)

i) Advertisements – “I’m a PC and I invented Windows 7”

ii) New taskbar - ‘Pin’ - favorite programs to taskbar for quick access

iii) Built for speed - faster - reduced memory footprint (more efficient)

iv) Windows Touch -Touch screen navigation

h) Windows 8

i) New GUI – Tiles instead of Start menu

ii) Integrating with cloud

i) Windows 10 (pg 81)

i) Cortana – AI search tool

ii) MS Edge – new browser

iii) Virtual Desktops – switch desktop appearance

9) MAC OS

a) on Apple MacIntosh computers - 1984

i) 1st GUI – influenced by Xerox PARC research

ii) late 1980’s most advanced PC OS

iii) named System 1 thru System 7 – 1984 - 1991

b) Versions - OS X – 2001 thru today

(1) Each new version of OS X given cat names (eg: Cheetah, jaguar, Snow Leopard)

(2) OS X completely redesigned from prior MAC Oss

ii) Cheetah (2001) – iMovie, iTunes

iii) Mountain Lion (2012) - added popular iPad feature to desktop OS – eg: iCloud

iv) Mavericks (2013) – improved integration with mobile devices – iPad, iPhone

c) No virus threats – most MAC users – no anti-virus software

d) Hackintosh – Ethics section page 82

i) PC modified to run OS X operating system instead of Windows

(1) New Macs – Intel Processors like PCs

(2) Modified PC can now run using OS X

10) Unix and Linux

a) Unix

i) developed 1969 – AT&T’s Bell Lab

ii) early multitasking OS

iii) folders (aka: directories) Unix innovation

(1) influenced DOS

iv) network capabilities built-in

(1) also a popular multiuser operating system (networking – Chapter 4)

v) problems

(1) too many variations

(2) difficult to use

(a) GUI’s now available

(b) Competing GUI’s – Motif, Open Windows, Gnome

(c) Unix problem – too much variety

b) Linux

i) Unix variant –

ii) created 1991 – Linus Torvalds

iii) open source – available to use/modify

(1) developed by thousands of programmers

(2) distributions (aka distros) – various features created by these developers

(a) eg: system utilities, games and an office suite (modeled after MS Office)

(b) GUIs – Windows or MAC OS look and feel

iv) cross platform - runs on PC, MAC, iPods

v) free

(1) must buy Linux CD – includes Linux apps, utilities and GUI

vi) small desktop OS market share - < 2%

11) Embedded Operating Systems – page 84

a) overview

i) Specialized OS – small, limited specialized functionality – run on simple machines

ii) Apps – ATMs, video games, smartphones, digital cameras, appliances etc

b) Mobile Devices

i) Mobile operating systems – most advanced of the embedded OSs

(1) Lots of touchscreen functionality – now being adopted on desktops

ii) Used on smartphones

(1) Windows CE

(2) iOS – used on iPhones, iPads and iPods – scaled down version of OS X

(3) Android – Samsung phones? –scaled down version of Linux

12) Network Operating Systems - NOS

a) Purpose

i) Designed for network use – Corporate users

b) Win NT (1993) - precursor to Windows Server 2019

c) Windows Server

i) Similar to Win desktop OS (beginning with Vista)

(1) plus additional features for client/server environment

(2) Security – control access to centralized data

(3) Remote Administration – centralized updates/backups – application changes

(4) Web Server –

(a) makes web pages available to users

(b) host web applications (like Tripod hosts my web page)

d) Unix/Linux – Server OS as well as Standalone OS

e) MAC OS X Server – Apple’s Server OS

13) Home Networks

a) Peer to Peer (P2P) – instead of client/server

b) Simpler – included in desktop OS – no additional NOS software require

c) All nodes equal – share resources with each other

i) Eg: shared printer in home network

14) File Management – page 87

a) Purpose

i) Organize your files

b) Definitions

i) Files contain data/programs

(1) Data file – syllabus.docx

(2) Program file – Word.exe

ii) Folders contain files

(1) User folder

(a) Windows automatically sets up for each user based on each user account

(b) You have a CCAC user account that only you can access

iii) Windows created subfolders

(1) Documents, Music, Pictures and Videos – Libraries automatically created

iv) File Explorer – File Manager for Windows OS – pic page 88

c) File Management Functions

i) View files & folders - Size, type, creation date

ii) Move, copy, rename, delete files

iii) Create new folders

(1) Way to organize work –

(2) Hanging folder analogy

(3) My PC- CCAC, House, Kids, Madden

15) Understanding File Names

a) Files contain data/programs

i) names to store/retrieve

(1) save syllabus.docx (logical) not store memory contents to clusters 73 –75

ii) File names have extensions

(1) Identify file type

(2) .docx (in Syllabus.Docx) – MS Word file

(3) Others – chart page 91

(a) .exe (program file), .xlsx (MS Excel file), .jpeg (image file)

iii) Clicking on a file to open it automatically opens the program that created it

(1) Since .docx files are created by MS Word, clicking on a .docx file automatically opens MS Word

iv) File properties can be viewed with File Explorer – pic page 92

(1) File type (extension), size (# bytes), creation date

16) File Compression

a) reducing file size – save storage - efficient transfer

b) needed for media files very large - audio, video, photo

c) CODECS – algorithms for Compression/Decompression

i) Lossless – file can be completely restored

(1) Text files – lots of redundancy

(2) replaces repeating byte patterns (eg:spaces)

ii) Lossy – imperceptible data lost – cannot be recovered

(1) Used on media files

(a) Very large with unnoticeable detail

(b) Two pictures on page 94

(i) Left uncompressed – TIFF file – needed where every detail counts – medical image

(ii) Right compressed – 25 times smaller – JPEG – good enough for everyday pictures

(c) MPEG – common compressed file type for video –

(i) for transfer to YouTube

(ii) YouTube reconverts to Flash for viewing on Web – need Flash player for most Web videos – download when needed

17) Search Utility (included with Windows OS)

a) Find files

b) Used week one?

i) find calculator program

ii) Found Syllabus (if accidentally stored in unknown folder)

c) search box – bottom left on Task bar

18) Storing Files in the Cloud

a) Cloud storage – allows access to files from different devices

i) Create file on PC - Save it to the cloud - Access from an iPad

b) OS X – iCloud -5GB online storage – top picture page 98

c) Windows – OneDrive – 7GB online storage – picture page 99

d) Not intended for backup purposes – due to 7GB limitation – won’t backup your entire hard disk – 930 GB on my hard disk