Operating Systems

Home

Curriculum Vitae

Interests

Javascript




Types of Operating Systems


windows







"For individuals who demand the most from their computing experience"

Features include:

  • Instant messaging, voice, video, and application
    sharing
  • NTFS security
  • Improved performance
    -work on multiple tasks at once
    without degrading
    performance or reliability
  • Improved user interface for fast
    work management



Linux







"More than a mere server and desktop OS"

Features include:

  • Built-in convenience and security
  • Personal Firewall protection
  • Netscape 6.1, StarOffice, Games ICQ, Instant Messenger, video conferencing



Mac







"OS X unleashes the full potential of the Macintosh"

Features include:

  • Redesigned Finder for viewing file systems
  • Large buttons instantly take you to the most frequently accessed areas
  • Aqua interface features liquid color, translucence, and depth

Operating Systems


An operating system is a collection of system programs that together control the operation of a computer system. It organises and controls the hardware i.e. it's the software that enables the programs we use. All desktop PCs have operating systems; the most common being the Windows family (Windows 95, 98, 2000, NT and XP), Unix (Linux) and Mackintosh operating systems.

Functions of the operating system

  • It manages the hardware and software resources of the computer system e.g. processor, memory, disk space etc.
This is vital as programs/inputs compete for the attention of the central processing unit (CPU) and demand memory/storage for their own purposes.
  • It provides a stable, consistent way for applications to deal with the hardware
A consistent application program interface (API) allows a software developer to write an application on one computer, knowing that it will run on another similar computer. Even if a particular computer is unique, an operating system can ensure that applications continue to run when hardware upgrades and updates occur, because the operating system and not the application is charged with managing the hardware and the distribution of its resources.
  • General Purpose OS: It provides the ability to run a number of different programs

  • Dedicated OS: An operating system designed for a specific purpose

  • Single-User, Single Task: One user can do one task at one time e.g. Palm OS for palm computers

  • Single-User, Multi-Tasking:One user can have several programs in operation at the same time: Desktop and laptop operating systems e.g. Windows 98 and Mac OS

  • Multi-user: Allows many different users to take advantage of the computers' resources simultaneously e.g. unix and mainframe operating systems(MVS).

Note: It's important to differentiate between multi-user operating systems that support networking. Windows XP support thousands of networked users, but the operating systems themselves aren't true multi-user operating systems. The system administrator is the only "user"; the remote user logins are a program being run by the administrative user.
The operating system's tasks can be divided into 5 categories:
  1. Processor management
  2. Memory management
  3. Device Management
  4. Storage Management
  5. User interface
Process Management ensures that each process and application receives enough of the processor's time to function properly. A process is a portion of a program in some stage of execution.
The operating system controls and schedules processes for execution by the CPU. In a single-tasking system, scheduling involves suspending the execution of a running program long enough to deal with interrupts and user input. Interrupts are signals sent by the hardware or software to the CPU requesting its attention. The operating system will schedule the priority of the processes and deal with them in turn (pre-emptive switching and cooperative switching). In a multi-user operating system the execution of applications must be arranged so that you believe that there are several things happening at once.
A Process Control Block (PCB) contains all the info needed to keep track of a process when switching (ID Number, location, states of various flags and switches, priority and input/output devices used by the process etc.

Memory Management
  • It ensures that each process has enough memory in which to execute
  • it ensures that it cannot run in the memory of another process, nor be run into by another process.
  • Disk Storage is the only memory type that must be managed by the operating system
Device Management A driver is a special program which acts as a translator between the electric signals of the hardware and high level programming languages of the operating system and application programs. Managing all the resources of computer system is a large function of the operating system. Drivers take data that the operating system has defined as a file and translate them into streams of bits placed in specific locations on storage devices, or a series of laser pulses in a printer.

Storage Management
  • The different types of memory in the system must be used properly so that each process can run most effectively.
A Graphical User Interface (GUI) brings structure to the interaction between a user and the computer. The core operating system functions, the management of the computer system, lie in the kernel of the operating system.

The Future...

The continuing improvements in technology and computing means that operating systems will have to change and evolve to keep pace, but the core management and interface functions will remain.

[Top]