James Tam Introduction to software Concepts covered What is software Categories of software and the differences between each The relation between software and hardware

James Tam What is software? The instructions that tell the hardware what to do. 1)Balance my check book. 2)Do taxes 3)Print out my resume 4)::

James Tam Categories of software Application programs (applications) Operating systems Compilers

James Tam Common types application programs 1)Word processors 2)Spreadsheets 3)Databases 4)Presentation software 5)Web browsers

James Tam 1) Word processors (e.g., MS-Word) Lots of features (to be covered in lab) For text editing Images Customizable Built in Help And much, much more!

James Tam 2) Electronic spreadsheets (e.g., MS-Excel) Deals with rows and columns of numeric data Performs many calculations Many predefined mathematical functions (e.g., sum, average, min, max etc) Makes graphical representations of the data (e.g., graphs) Allows you perform a “what if” analysis

James Tam 3) Databases (e.g., MS-Access) Allows data to be stored, organized, maintained and retrieved.

James Tam 4) Presentation software 1 (e.g., PowerPoint) Often used in presentations The computer equivalent of transparencies Allow for dynamic presentations (pictures, animations, sound) – can be overdone 1 It is listed in Beekman under the name “Presentation graphics”

James Tam 5) Web browsers Internet Explorer Netscape

James Tam Operating systems: What do they do? 1)Act an an intermediary between the user and the hardware (mediator) 2)Manage the resources of the computer (parent) 3)Some may act to secure some parts of the computer (security)

James Tam The operating system: The Intermediary between the user and the hardware (operating system)

James Tam Intermediary between the user and the hardware (e.g., hard drive)

James Tam Manage system resources (parent)

James Tam Manage system resources e.g., processor time A = B + C (Multi-tasking operating system)

James Tam (Single tasking operating system) A = B + C

James Tam Manage system resources e.g., memory management A = B + C RAM

James Tam Manage system resources (virtual memory) A = B + C RAM Hard drive

James Tam 3) Securing information on the computer (security)

James Tam Single user computer: security not a big issue Mary A2

James Tam Multiple user system: there is a need to secure the information Separates and protects the work of different people who are working on a computer. A2 Bill Mary George A2 Bill’s A2 Mary’s A2 George’s A2

James Tam Securing the information on the computer This is not always done! Single user operating systems don’t do this. MS-DOS, Windows 95, 98 Multi user operating systems do. Windows NT, Windows 2000, Windows XP, Unix  203 lab computers

James Tam User Interfaces Acts as the intermediary between the user and the software Software (e.g., operating system) User Interface

James Tam Types of user interfaces GUI based Command line based

James Tam GUI (Graphical user interface) based operating systems Examples Windows ( ‘ 95, ’98, ME, NT, ‘2000, ‘XP ) Apple ( OS10) Characteristics Many! Graphical (e.g., uses icons that are selectable with a mouse)

James Tam Command line based software Example Unix (Linux) MS-DOS Characteristics Type in commands at a “command line”

James Tam A WIMP(Window, Icon, Menu, Pointer)-based operating system: Windows

James Tam An alternative to the desktop: Pad++ Pad++: A Zoomable Graphical Sketchpad for Exploring Alternate Interface Physics Bederson et al Journal of Visual Languages and Computing 7, 1996

James Tam An alternative to WIMP: The task gallery

James Tam Compilers (translators) 圣诞快乐和新年好 ! Huh? Merry Christmas and Happy New Year! Same to you buddy! Real life translation

James Tam Compilers: translate between languages (high level view) Do my taxes , , … The compiler

James Tam Compilers: Actual view 1) A programmer writes a computer program 2) The compiler translates the program into a form that the computer can understand 3) An executable program is created Anybody who has this executable on their computer can then run (use) it.

James Tam Relating software back to hardware: high level view of a computer (again)

James Tam How does your computer look when it’s off?

James Tam What happens when you turn on your computer (start-up): Step one execute instructions in BIOS. To From

James Tam What happens when you turn on your computer (start-up): Step two load the operating system. To From

James Tam At the desktop (OS running after start up)

James Tam At the desktop (run an application with mouse): Step 1 Operating system interprets mouse information ??? What happened?

James Tam At the desktop (run an application with mouse): Step 2 Operating system loads application FromToApplication selected with mouse

James Tam Summary (important points) What is software What are different categories of software What are example types of application programs What do operating systems do How do compilers work The relationship between hardware and software