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Understanding the Role of an OS in Managing Hardware and Software, Study notes of Operating Systems

An overview of operating systems (os), their definition, major components, and jobs. The os acts as the master control software, managing hardware and software resources, and making system usage easier for users. It performs three primary jobs: command interpreter, interface between hardware and software, and resource manager. The document also covers concepts like multi-tasking and virtual memory.

Typology: Study notes

Pre 2010

Uploaded on 07/22/2009

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18 October – Day 16
CSC 350 Review
OS Job
OS Modules
function
structure
---CSC350 notes---
I. Operating Systems Overview
A. Systems Software
What is software? define …
note: great use for CS:AO! If you don’t recall a term, topic, etc –
consult this text
Three major components of systems s/w: booting software, translation
software, OS
Why is systems software different from application software or
programming language?
Looks “inward;” makes using the H/W easier for users and other S/W
3 Levels/layers of software built upon the hardware
Application Package – solve user problem
Programming Language – create application package
-------------------------------------------
Systems S/W – manage system
First two levels look “outward” to the user
Last level looks “inward” to the H/W
analogy: stewardship vs. evangelism
B. Operating System (OS)
Definition: Master control S/W
Goal: Control and manage the H/W and other S/W of the system
Operating system makes using the H/W easier for users &
applications
Three major jobs of an OS:
CSC 490 Course Notes and Outline, © Dr. Gary Locklair, Fall 2006
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18 October – Day 16 CSC 350 Review OS Job OS Modules function structure ---CSC350 notes--- I. Operating Systems Overview A. Systems Software What is software? define … note: great use for CS:AO! If you don’t recall a term, topic, etc – consult this text Three major components of systems s/w: booting software, translation software, OS Why is systems software different from application software or programming language? Looks “inward;” makes using the H/W easier for users and other S/W 3 Levels/layers of software built upon the hardware Application Package – solve user problem Programming Language – create application package


Systems S/W – manage system First two levels look “outward” to the user Last level looks “inward” to the H/W analogy: stewardship vs. evangelism B. Operating System (OS) Definition: Master control S/W Goal: Control and manage the H/W and other S/W of the system Operating system makes using the H/W easier for users & applications Three major jobs of an OS:

  1. Command Interpreter Portion of OS which inputs, interprets, and executes user commands User Interface portion of the OS used for level 1 problem solving by user Different types of commands a. OS commands Ex: ... Windows Explorer (one prime user i/f) Delete a file, etc b. Executable (eg, Application file name) Ex: ... menu, double-click file name, run windows
  2. Interface between H/W and other S/W Application packages can not work with hardware directly Operating system controls actual H/W functions Why? a. makes programming easier ... cout << “Hello”; don’t have to know about dot-matrix and pixels on CRT; OS handles it b. protects H/W from accidental bugs ... programming error could cause h/w to smoke; rather than 1000s applications with possible mistakes, OS protects h/w use
  3. Resource Manager Biggest job for a large computer system diagram large computer system processor and terminals (I/ O) Operating system must manage the use of resources Illustration: 10 users on 10 terminals running 10 different applications — One CPU can only service one user at a time “Do not I fill heaven and earth?” declares the LORD. Jeremiah 23: “Tricks:” a. Multi-Tasking Scarce resource is ... CPU Trick which gives the appearance of multiple simultaneous users algorithm: (i) OS gives each user a small portion of time (time slice, e.g. 50ms) in which to use the CPU
  • process manager – long term (or job) scheduler ensures system can handle a new job
  • file manager – locates application object code on storage
  • memory manager – places application package into RAM – address resolution
  • process manager – short term (or process) scheduler co-ordinates execution of job
  • during execution, instructions may invoke: device manager – for use of physical devices (keyboard, CRT, printer, etc) file manager – for use of data files memory manager – (virtual memory) process manager – (multi-tasking) 1 st^ part of “Giant Brains” video from “Machine that changed the world” series