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Operating Systems Dr. Fred Mtenzi 1 Teaching Approach • Lectures and labs – Wed 11.00 – 12.00 noon (Lecture) – Wed 14.00 – 15.00 am (Lab) – Thur 12.00 – 13.00 pm (Lecture) 2 Assessment methods • Written examination 70% • Continuous assessment 30% – Written test end of first semester. – Linux lab test. – Shell programming. 3 References • Understanding Operating Systems, 3rd Ed, I.M. Flynn and A. Mclver McHoes, (2001) PWS Publishing Company. • Operating Systems: Internals and design principles (2001), 4th Ed, William Stallings, Prentice Hall. • Modern Operating Systems, Andrew Tanenbaum(2001), 2nd Edition, Prentice Hall. • Operating Systems Design And Implementation 2nd Edition Andrew Tanenbaum, Albert Woodhull (1997), Prentice Hall. 4 References • Operating Systems Modern Perspective 2nd Edition Gary Nutt (2000), Prentice Hall. • Operating Systems A Systematic View 5th Edition William Davis, T.M. Rajkumar (2001), Prentice Hall. 5 Operating Systems Theory • To understand the OS is to understand the workings of the entire computer system, because it is the OS that managers each and every piece of hardware and software. • An OS is the ‘executive manager’, the part of the computing system that manages all of the hardware and all of the software. To be specific, it controls every file, every device, every section of main memory, and every nanosecond of processing time. 6 Operating Systems Theory • The OS has four subsystem managers: memory manager, processor manager, device manager and file manager. • Each of the subsystem managers must perform these tasks: – Monitor its resources continuously. – Enforce the policies that determine who gets what, and how much. – Allocate the resources when its appropriate. 7 Operating Systems Theory – Deallocate the resource – reclaim it when appropriate. 8 Understanding Operating Systems Part II: Operating Systems in Practice 12. 13. 14. 15. 16. MS-DOS Operating System Windows 2000 UNIX/Linux Operating System OpenVMS Alpha Operating System IBM OS/390 Operating System 9 Overview • Introduction • Operating System Components • Machine Hardware • Types of Operating Systems • Brief History of Operating Systems Development • Conclusion Software Components Developed Hardware Components Developed Operating Systems Developed 10 Components of an Operating System Operating system – part of the computing system that manages all of the hardware and all of the software – Controls every file, device, section of main memory & every nanosecond of processing time Operating system consists of • Memory manager • Processor manager • Device manager • File manager 11 Subsystems Must Work With Each Other 12 Tasks Performed by Each Subsystem 1. Monitor its resources continuously 2. Enforce the policies that determine who gets what, when and how much 3. Allocate the resource when appropriate 4. Deallocate the resource (reclaim it) when appropriate 13 Machine Hardware • Memory chips • Input/output devices (monitor, keyboard, printer) • Storage devices (disks, magnetic tape, card readers, drums) • Central Processing Unit (Arithmetic Logic Unit, registers, internal control, bus control) 14 Types of Operating Systems • • • • • • Batch (simple and multi-programmed) Interactive (time-sharing) Real-time systems Hybrid systems (combination of batch and interactive) Parallel (tightly coupled) Distributed (loosely coupled) 15 Brief History of Operating Systems Development Second Generation Job scheduling, JCL, faster I/O, spooling, batch, files 1940 1955 Recent Developments Distributed computing, personal computers, highspeed communication, multi-media 1965 1980 First Generation Third Generation Vacuum tube, single user, early operating systems Shared processing, multiprogramming, virtual memory, DBMS 1990 16 Key Terms • • • • • • • • • • batch system central processing unit device manager file manager firmware hardware hybrid system interactive system main memory mainframe • • • • • • • • • • • memory manager microcomputer minicomputer multiprocessing networking operating system processor manager real-time system software supercomputer workstation 17