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LBSC 690

LBSC 690. Session 7 Operating Systems. System Software. System software: All software designed either to control the computer system or to assist users in running applications or prog4rammers in developing software. It includes operating system and utilities.

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LBSC 690

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  1. LBSC 690 Session 7 Operating Systems

  2. System Software • System software: • All software designed either to control the computer system or to assist users in running applications or prog4rammers in developing software. • It includes operating system and utilities. • It also may include developmental software. • It is designed in layers.

  3. Operating system: • Set of programs that govern the operation of the computer system. • Provides such functional support as: • Memory management, interaction with peripheral, and execution of application programs. • Has two primary functions: • Facilitates computer resource sharing among competing users. • Transforms raw hardware of computer into a machine that can more easily be used.

  4. Virtual Machine • Input vs. output. • Memory. • Filing system. • Protection & error handling. • Program interaction. • Program control.

  5. Components of a PC/OS • Supervisor (Kernel). • I/O Manager & Device Drivers. • File manager. • Command Processor. • Transient Utilities.

  6. Functions • Supervisor: • Schedules & coordinates: acts as a traffic cop. • I/O Manager: • Manages device drivers; provides device independence. • File manager: • Allocates and manages files and their locations. • Directories and translation.

  7. Functions (Cont’d.) • Command Processor: • Types of command interfaces: • Command-line: DOS, e.g. • Menu driven. • Visual interface: • Windows, MacIntosh. • Combinations of above.

  8. Types of PC OS • MS-DOS/PC-OS • Microsoft Windows (Many Versions) • Unix (Many Versions) • Solaris • MacIntosh O/S • Next • Linux • Palm O/S • Embedded Real-Time Systems

  9. Windows 98 Architecture • Reference Handout: Figure 8.1. • Layered architecture: • Ring 0: Inner core. • Ring 3: Virtual machine manager. • Applications run in virtual machines: • DOS: equivalent to a single 8086 oper. env. • 16 bit applications: share memory space. • 32 bit applications use unique address spaces.

  10. Windows NT Development of a New Technology (NT)

  11. Marketing Requirements • Portability. • Multiprocessing and scalability. • Distributed computing. • POSIX (Portable Operating System Interface based on UniX) compliance. • Government certifiable compliance.

  12. Windows NT Models • Layered System Model. • Ref. Handout, Fig. 2-2. • Client/Server Model. • Ref. Handout, Fig 2-3 & 2-4. • Object Model. • Symmetric Multi-Processing Model. • Ref. Handout, Fig. 2-5.

  13. Definitions & Concepts • Program: Static sequence of instructions and associated data. • Process (Job): Dynamic initiation and execution of a program. • Thread: An executable entity of a process. • Multithreading: Capability to run in two or more locations using multiple threads. • Sometimes called multitasking.

  14. Definitions (Cont’d.) • Multiprocessing (MP): An operating system’s simultaneous execution of two or more threads on different processors. • Asymmetric multiprocessing (ASMP): An MP system that always selects the same processor to execute the operating system code. • Symmetric multiprocessing (SMP): A multiprocessing system that allows operating system code to run on any free processor in a multiprocessing system.

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