Understanding Operating Systems: Components, Types, and History, Slides of Operating Systems

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CS 362

Operating Systems

INTRODUCTION

What is an Operating System?

Computer System Components

1. Hardware

• provides basic computing resources (CPU, memory, I/O devices).

2. Operating system

• controls and coordinates the use of the hardware among the various application programs for the various users.

Resource Management

Computer System Components

3. Applications programs
   • define the ways in which the system resources are used to solve the computing problems (compilers, database systems, video games, business programs).
4. Users
   • people, machines, other computers

Operating System Definitions

• Resource allocator
  • manages and allocates resources.
• Control program
  • controls the execution of user programs and operations of I/O devices.
• Kernel
  • the one program running at all times (all else being application programs).

How Using a Computer Used to

Suck

A Little History…

Mainframe Systems

• Resident monitor
  • initial control in monitor
  • control transfers to job
  • when job completes control transfers back to monitor

Memory Layout - Simple Batch System

OS Features - Multiprogramming

• I/O routine supplied by the system.
• Memory management
  • the system must allocate the memory to several jobs.
• CPU scheduling
  • the system must choose among several jobs ready to run.
• Allocation of devices.

Time-Sharing Systems

• The CPU is multiplexed among several jobs

that are kept in memory and on disk (the CPU is allocated to a job only if the job is in memory).

• A job swapped in and out of memory to the

disk.

Desktop Systems

• Personal computers
  • computer system dedicated to a single user.
• I/O devices
  • keyboards, mice, display screens, small printers.
• User convenience and responsiveness.

Desktop Systems OS

• Can adopt technology developed for larger operating system
• Often individuals have sole use of computer and do not need advanced CPU utilization of protection features.
• May run several different types of operating systems (Windows, MacOS, UNIX, Linux)

Parallel Systems

• Advantages of parallel system:
  • Increased throughput
  • Economical
  • Increased reliability
    • graceful degradation
    • fail-soft systems
  • Increased capability

Parallel Systems (Cont.)

• Symmetric multiprocessing (SMP)
  • Each processor runs under a single copy of the operating system.
  • Many processes can run at once without performance deterioration. - This does not necessarily mean that there is any improvement…
  • Most modern operating systems support SMP