1) Introduction to Operating Systems
1) Introduction to Operating Systems IT1205
Popular in OPERATING SYSTEMS
Popular in Information technology
This 3 page Class Notes was uploaded by Ashleigh148 on Wednesday November 11, 2015. The Class Notes belongs to IT1205 at Nanyang Polytechnic taught by TEO WEI LING MICHELLE STF-SIT; YOW MEI LING STF-SIT; CHUNG JASON STF-SIT; in Fall 2015. Since its upload, it has received 82 views. For similar materials see OPERATING SYSTEMS in Information technology at Nanyang Polytechnic.
Reviews for 1) Introduction to Operating Systems
Loved these! I'm a horrible notetaker so I'll be your #1 fan in this class
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 11/11/15
Chapter 1 Introduction to Operating Systems What is an Operating System OS 0 A program that acts as an intermediary between the user of a computer and the computer hardware 0 Provides an environment in which user can execute programs in a convenient and efficient manner 0 Useless by itself Computers and Software 0 Consist of software and hardware 0 Software is differentiated according to its purpose Application software is software that allows the user to perform some intended task function or activity and includes productivity tools System software provides an interface with hardware and serves as a platform for running programs and maintaining the efficiency of the system It can be divided into operating systems and utility programs System Software 0 Allows human users to interact with the computer 0 Provides tools and subassemblies used with application programs 0 Independent of individual applications but common to all of them C library functions A window system A database management system Resource management functions The Operating System Resource What is a Resource It is what s necessary for an executing program to run Memory the space on a disk the CPU etc In fact the Operating System can be viewed as a resource manager 0 An OS creates resource abstractions and manages resource sharing Resource Abstraction When an OS hides the actual tasks needed to manage and use resources Allows the user programs to use those resources via simpler commands for accessibility Makes it easy for user programs to use resources in a computer system oWriting a file to disk oDisplaying textgraphics on screen oRunning an application Makes usage simple but limits flexibility Some operations become easy to perform while others may be impossible to accomplish Resource Sharing 0 Spacemultiplexed sharing The resource is divided into two or more distinct units with each unit being assigned to different processes 0 Timemultiplexed sharing The entire resource is assigned to a process for a period of time then it s assigned to another process and so on Multiprogramming The technique for sharing the CPU among runnable processes 0 Process may be blocked on IO 0 Process may be blocked waiting for other resource including the CPU 0 While one process is blocked another might be able to run 0 Increases CPU utilization OS Strategies The general characteristics of the programmer s abstract machine 1 2 How will the computer be used Is human interaction important 3 Will there be more than one person using 4 Is response time critical Strategies Batch processing 1 Uses multiprogramming Job file of OS commands prepared offline Batch ofjobs given to OS at one time OS processes jobs oneaftertheother No humancomputer interaction OS optimizes resource utilization Batch processing as an option still used today Timesharing Uses multiprogramming Support interactive computing model Illusion of multiple consoles Different scheduling amp memory allocation strategies than batch Tends to propagate processes Considerable attention to resource isolation security amp protection Tend to optimize response time Personal computer amp workstations Others a Process control amp realtime b Network c Distributed d Small computers
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'