Operating System (OS) Basics

Operating System Basics

Software (applications)

Operating System (OS)

Hardware

Examples of Software Applications

Word processor Web browser E-mail client Multimedia player

Examples of Operating Systems

MS-DOS Windows XP Windows 7 Mac OS X Ubuntu Linux

Examples of Hardware

CPU RAM Keyboard Mouse Monitor

Operating System Basics

Operating System (OS) Provides user interface(s)

WIMP! Windows, Icons, Menus, Pointer (mouse)

Interfaces directly with the hardware e.g., device drivers Input devices Ouput devices

File management Monitors and manages system activities

Graphical User Interface (GUI)

Name GUI elements in applications

Name GUI elements in an OS

Where does input come from?

keyboard mouse tablets scanning pens OCR – Optical Character Recognition MICR – Magnetic Ink Character Recognition Webcam microphone Etc.

...and output?

monitors (CRT, LCD, etc.) printers speakers Braille output monitors

File management

Create files Delete files Search for files Move files Navigate file tree Create folders Etc.

More OS Functions

Communicating with peripherals keyboard, mouse, monitor, printer, etc.

Coordinating concurrent processing multiple programs (processes) running at the same time

Memory management each program has their own space in memory

Resource monitoring processor time, memory usage, etc.

Accounting and security users, permissions, security logs, etc.

Program and data management programs reading/writing to files

Multi-processing/Multi-tasking

Memory allocation Load program from hard drive into a section

of memory (RAM) Time-slicing

Giving a particular program a “slice” of time to run

Priority A program can be given “priority” if it’s more

important (e.g. window in focus)

Virtual Memory

What do you think happens when you run too many programs and all of the memory is used up?

Virtual Memory Terms

Paging / Swapping Moving program data between memory

and disk Where do you see this stuff?

pagefile.sys in windows /swap space in linux Whenever you use up all your RAM and

your hard drive goes crazy.

Discussion: Why are there different operating systems?

Mac OS X vs. iOS Ubuntu Linux vs. Android

Advantages?

How does the OS represent hardware devices?

Hardware complexities are hidden from the user by the OS

Hardware is simplified and represented virtually by the OS

Examples Mouse pointer File tree and drive letters Others?

OS Hardware Communication

How does the OS know “when” to communicate with hardware?

Interrupt vs. Polling What do you think they mean?