lect2 - Intro to Information Systems I System Application...

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ISYS 101 Lecture #2 1 Intro to Information Systems I ISYS 101 Glenn Booker
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ISYS 101 Lecture #2 2 System Software System software includes the operating system (OS) and utilities The operating system performs the basic functions for a computer to be a computer Communicate between software and hardware Read from and write to storage Manage memory Run applications
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ISYS 101 Lecture #2 3 Operating System The main part of the operating system is the kernel, which is always in memory (“resident”) when the computer’s running Other parts of the operating system are called upon as needed (“non-resident”) Operating systems are CPU-specific You can’t run Windows on a G4 processor
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ISYS 101 Lecture #2 4 Operating System DOS was a single tasking operating system – you could only run one program at a time Most OS’s are multitasking – they can run many programs at once One is the foreground application, the others are background applications
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ISYS 101 Lecture #2 5 Multitasking Older OS’s (Windows 3.1) used cooperative multitasking – the foreground application uses all of the CPU’s attention Newer OS’s (MacOS 8-X, Win NT) use preemptive multitasking, which isolates each application in memory Even if an application crashes, the operating system doesn’t
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ISYS 101 Lecture #2 6 Multithreading, Multiprocessing Within one application, multithreading allows several tasks (“threads”) to be done at the same time Most modern OS’s use multithreading Multiprocessing (MP) is when the computer has more than one CPU For symmetric MP, each thread can be assigned to a different CPU
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ISYS 101 Lecture #2 7 Memory Management Memory (RAM) is divided into partitions for each application If RAM is limited, part of the hard drive can become virtual memory Chunks of memory are divided into “pages” to pass in and out of virtual memory Pages are written in a swap file on hard disk
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ISYS 101 Lecture #2 8 Interfaces Hardware interfaces are controlled by programs called device drivers Most are installed automatically User interfaces are Command line (DOS, UNIX) Menu-driven (CMOS – see later) Graphical user interface (MacOS, Windows)
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ISYS 101 Lecture #2 9 User Interface The user interface lets the user Gain access to the computer (log in) Run applications Manage disks and files Shut down the computer safely (necessary since DOS)
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ISYS 101 Lecture #2 10 Types of Operating Systems UNIX is a 30+ year old family of operating systems Mostly used for servers and workstations Dependable and very powerful, but hard to learn and somewhat obtuse (rename = mv) Two major subfamilies: IBM System V and Berkeley BSD
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ISYS 101 Lecture #2 11 Major UNIX Brands IBM AIX Sun Solaris, SunOS Apple MacOS X SGI Irix HP HP/UX DEC/ Compaq Tru64 UNIX On Intel-based computers, SCO and BSD are also available.
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This note was uploaded on 11/15/2011 for the course I SYS 201 taught by Professor Meservy during the Winter '11 term at BYU.

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lect2 - Intro to Information Systems I System Application...

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