System Software CSCI-N 100 Department of Computer and Information Science

Operating System A set of programs that perform certain functions Starting the computer Managing programs Distributing memory Coordinating the processor and peripherals Enabling user interaction with the computer

Starting the computer Cold boot – power is turned off O/S in ROM (read-only memory) loads BIOS (basic input/output system) into computer memory BIOS conducts Power on self-test (POST) to check for operability BIOS searches for O/S  CMOS (complimentary metal-oxide semiconductor) determines where to look O/S components (kernel) loaded into memory from storage O/S takes control of computer

Managing programs Single-tasking Run one application at a time Multi-tasking The ability to run more than one program at a time Foreground – program in use Background – idle program Multi-threading Multiple parts (thread) running simultaneously Multiprocessing Dual core processors or multiple processors

Managing Memory Allocates memory area for each running program Keeps programs from leaking into one another  Failure results in corrupt data, programs ‘crash’, error messages  CTRL + ALT + DEL used to close corrupt program Virtual memory an extension of RAM  Data/instructions swapped between RAM and hard drive Works with direct memory access (DMA) to control peripherals access to RAM

User Interface Part of the O/S that lets user and computer ‘talk’ to each other Types of operating systems Command line  Requires user to type keywords/commands to enter data/give instructions Graphical User Interface (GUI)  Uses little graphics – icons  User uses a pointing device to enter data/commands Mouse Joystick Keyboard Other types

Operating Systems MS-DOS UNIX LINUX MAC OS WINDOWS

MS-DOS (command line)

UNIX (command line) Developed by AT&T in 1970s First preemptive multitasking system Developed concepts of file management and path names Client/server networking system Widely used by corporations

LINUX - Developed in 1991 by UNIX, Competes with Windows and MAC, Powerful and free

MAC OS – First GUI (1984)

WINDOWS – 3.X Includes Windows 3.0, 3.1, 3.11, and Windows for Workgroups 3.1 Not a true operating system Uses cooperative multitasking

WINDOWS Windows 95 True operating system Uses preemptive multitasking Downward compatible with DOS Considered a transitional system

System Utilities System utilities are programs that help the operating system manage the computer system’s resources. Types of utilities: File management File finders Backup utilities Antivirus software File compression Disk scanning File defragmentation

File Finder - File finders are programs that enable the user to find files on a storage device

File management Known as a file manager. Enables the user to perform various tasks with files, folders, and directories on storage devices. Tasks include: Creating folders Saving, deleting, copying, and moving files and folders Examining the contents of files Launching application programs

File Compression - A file compression utility reduces the size of a file.

Disk Scanning - A disk scanning utility is a program that detects and fixes physical and logical problems on storage devices

File Defragmentation - A file defragmentation utility is a program that moves data on a storage device to improve performance.

Apple's 1984: The Introduction of the Macintosh in the Cultural History of Personal Computers by Ted Friedman Revised version of a paper presented at the Society for the History of Technology Convention, Pasadena, California, October Slide 13

Resources