1 Operating System Software What, Where, Why, and How? Startup routines ROM BIOS POST Device Drivers User Interface – Text or GUI Menus and dialog boxes

2 O/S Software Services Program Support RAM Supervising I/O Scan codes Print queue Managing the file system Partitions (drives) and subdirectories

3 O/S Software Resources Allocating memory Generating error messages Optimizing system performance Providing troubleshooting tools

4 O/S Software Genealogy DOS – PC, MS, IBM versions Command-line interface O/S or command prompt Used for troubleshooting under W2K UNIX vs. GNU Windows operating environment Booting and handling file functions required DOS

5 Windows 95/98 Windows 95 – replaced DOS GUI Four service versions Features similar to those of NT 4.0 FAT32 file system – supports more clusters on a hard drive; smaller cluster size; larger drive size NTFS file system – uses a Master File Table instead of FAT; each file stores file data

6 Windows 95/98 Enhancements Document-oriented Object-oriented System architecture multi-threaded – separate code segments multitasking – separate programs Virtual DOS Machine – complete operating environment for a DOS program

7 Windows 95/98 Advantages Plug and Play instead of DIP switches Hardware support DVD and PCMCIA USB and Firewire Network support –peer to peer Web Integration – active desktop

8 Windows 2000 Began as NT 5.0 Support for newer processors Plug and Play support ACPI Device Manager Support for a variety of file systems Control for space used for systems