1 what is an operating system? csc330patricia van hise
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What is an operating What is an operating system?system?
CSC330 Patricia Van Hise
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What are the components of a computer system?
A computer system consists ofhardwaresystem programsapplication programs
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What is an Operating System?
A program that acts as an intermediary between a user of a computer and the computer hardware.
Operating system goals: Execute user programs and make solving
user problems easier. Make the computer system convenient to
use. (User interface, API) Use the computer hardware in an efficient
manner.
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A Computer SystemA Computer System
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Functions of an OS Interface
Acts as an abstract virtual machine Hides the details from user Control execution of programs and operations of control
devices
Resource manager Maximize system utilization and/or performance
Time and space Sharing of limited or expensive physical resources Provides Protection
File storage, network communications, etc.
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History of Operating Systems First generation 1945 - 1955
vacuum tubes, plug boards
Second generation 1955 - 1965 transistors, batch systems
Third generation 1965 – 1980 ICs and multiprogramming
Fourth generation 1980 – present personal computers
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Structure of a typical FMS job – 2nd generation
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Multiprogramming system three jobs in memory – 3rd generation
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Today’s Range of Operating Systems
Mainframe operating systems Server operating systems Multiprocessor operating systems Personal computer operating
systems Real-time operating systems Embedded operating systems Smart card operating systems
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Migration of Operating-System Concepts and
Features
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Computer Hardware Review
Bus
Components of a simple personal computer
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(a) A three-stage pipeline(b) A superscalar CPU
The Von Neumann Cycle and Beyond
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numbers shown are rough approximations
Typical memory hierarchy
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One base-limit pair and two base-limit pairs
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Computer Hardware
Structure of a disk drive
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Structure of a large Pentium system
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Input/Output•An I/O device consists of two parts:
•Controller - chip that physically controls the device•The device itself
(The controller presents a simple interface to the operating system.)
•The software needed for each I/O device is called a driver.
•A driver gives commands to the controller and accepts its responses, and must run in kernel mode as part of the o.s.
•A device must have a different driver for each operating system it supports.
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3 Methods of I/OProgrammed I/O
Driver starts I/O and polls device to see if done;Busy wait
Interrupt drivenDriver starts device; driver returns control to OS. OS
blocks the caller and looks for other work to do.Device sends a signal, or interrupt, to the OS toindicate completion. OS then unblocks caller.
Direct Memory Access (DMA) - for high-speedI/O - transfers entire block of data with 1 interrupt
rather than 1 interrupt per byte.
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