GRAP 3175 Computer Applications for Drafting Unit V Operating Systems

1. GRAP 3175Computer Applications for DraftingUnit VOperating Systems

2. System SoftwareOverview • Consists of programs designed to perform tasks associated with directly controlling and utilizing computer hardware. • Operating systems are the most important system software

3. System SoftwareOverview • Other system software includes: • data management software • computer-language software • FORTRAN, COBOL, BASIC, etc.

4. Operating SystemDefinition • Core set of programs that control & supervise the hardware, & provide services to other system software, application software, & users. • The portion of the operating system in use resides in main memory. • NO one universal operating system

5. Classes of Operating Systems • Proprietary operating system — designed for use by a specific computer architecture. • MS-DOS & PC-DOS - IBMs and compatibles using Intels • Apple Macintosh - runs a Macintosh computer

6. Classes of Operating Systems • Generic operating system — designed for use by a wide variety of computer architectures. • Unix - runs on the high end of both Intels and Motorolas

7. Parts of an Operating System • Control Programs • Manage computer hardware and resources. • Service Programs • External operating system programs that provide a service to the user.

8. Control Program Functions • Resource management — allocate computer resources such as:CPU time, main memory, secondary storage, and input & output devices • Data-management — govern the input and output of data and their location, storage, and retrieval

9. Control ProgramsFunctions • Job management — prepares, schedules, controls, and monitors jobs submitted for execution. • Job control language (JCL) — allows a user to specify what a job requires in terms of computer resources and operating systems services. • JCLs can be complex on a mainframe. Or • One-line commands on a PC: DIR, ERASE, etc.

10. Service Programs • Loaded separately into main memory • FORMAT

11. Operating System Capabilities

12. Number of Users • Single-user Processing — allows only one user at a time to access a computer. DOS • Multiuser Processing — allows two or more users to access a computer at the same time. Large computers.

13. Number of Tasks • Single Tasking — allows only one program to execute at a time, and the program must finish executing completely before the next program can begin. MS-DOS. • Context Switching — allows several programs to reside in memory but only one to be active at a time.

14. Number of Tasks • Multitasking — allows a single CPU to execute what appear to be more than one program at a time. The CPU switches its attention between two or more programs in main memory as it receives requests for processing from one program and then another. Windows

15. Types of Processing • Multiprocessing — allows the simultaneous, or parallel, execution of programs by a computer that has two or more CPUs. Supercomputers and Mainframes. • Multithreading — can support several simultaneous functions with the same application.

16. Types of Processing • Interprocessing — dynamic linking, allows any change made in one application to be automatically reflected in any related, linked application. • Time Sharing — allows multiple users to access a single computer. Large computer operating systems. The CPU is shared. If too many users delays results. TSO

17. Types of Processing • Virtual Storage — (virtual memory) allows you to use a secondary-storage device as an extension of main memory. • Real-time Processing — allows a computer to control or to monitor the task performance of other machines and people by responding to input data in a specified amount of time. Dedicated system

18. Types of Processing • Virtual-machine (VM) Processing — creates the illusion that there is more than one physical machine when in fact there is only one. Allows several users to operate as if each had the only terminal attached to the computer. Choose different operating systems. Supercomputers and mainframes.

19. Microcomputer Operating Systems

20. User Interface • Portion of the program that the users interact with. • text-based user interfaces — require a user to type the desired commands at a command line. DOS • graphics-based user interfaces — operate in the graphics mode • Operating Environments — using windows to enhance the operating s system. Windows 3.1

21. Most Common Operating Systems • DOS (PC-DOS, MS-DOS) • Windows: 95, 98, 2000, NT, and CE • Macintosh/Mac OS • UNIX and Linux

22. DOS • PC-DOS / MS-DOS • Single user, single tasking, text-based user interface • DOS 6.22 • Windows 3.1

23. Windows 95, 98 • Plug-and-Play • Windows 98 - integrates Internet into OS • Graphical user interface • Single user, multitasking, interprocessing

24. Windows NT • NT is not plug-and-play • High-end operating system • Network based • Security • NT 4.0

25. Windows 2000 • 2000 - combines NT & 98 • 2000, 2000ME, 2000 Professional

26. Windows CE • Designed for handheld / pocket PCs

27. Macintosh/Mac OS • Designed for MACs • Mac OS 9 • Virtual PC

28. UNIX and Linux • Multi-user, multitasking • Large number of built-in utilities suited for software developers • Difficult for novice users • Many versions of UNIX • Xenix, A/UX, etc.