Operating Systems (OS)

Operating Systems (OS)

1. What is a OS ?

   • An operating system or OS is a software program that enables the computer hardware to communicate and operate with the computer software. Without a computer operating system, a computer and software programs would be useless.
     • How it works?
       • Once the operating system has started up, it manages all of the software and hardware on the computer. Most of the time, there are many different programs running at the same time, and they all need to access your computer's central processing unit (CPU), memory, and storage. The operating system coordinates all of this to make sure each program gets what it needs.

2. Types of OS

   • Embedded
     • Embedded operating systems are designed to be used in embedded computer systems. They are designed to operate on small machines like PDAs with less autonomy. They are able to operate with a limited number of resources. They are very compact and extremely efficient by design.
   • Multi-user
     • A multi-user operating system allows multiple users to access a computer system at the same time. Time-sharing systems and Internet servers can be classified as multi-user systems as they enable multiple-user access to a computer through the sharing of time.
   • Distributed
     • A distributed operating system manages a group of independent computers and makes them appear to be a single computer.
   • Templated
     • In an o/s, distributed and cloud computing context, templating refers to creating a single virtual machine image as a guest operating system, then saving it as a tool for multiple running virtual machines . The technique is used both in virtualization and cloud computing management, and is common in large server warehouses.
   • Real-time
     • A real-time operating system is a multitasking operating system that aims at executing real-time applications. Real-time operating systems often use specialized scheduling algorithms so that they can achieve a deterministic nature of behavior. The main objective of real-time operating systems is their quick and predictable response to events. They have an event-driven or time-sharing design and often aspects of both.
   • Multi-tasking
     • A multi-tasking operating system allows more than one program to be running at the same time, from the point of view of human time scales.

3. OS functions

   • The two basic things that does an operating system are:
     • It manages the hardware and software resources of the system. In a desktop computer, these resources include such things as the processor, memory, disk space and more (On a cell phone, they include the keypad, the screen, the address book, the phone dialer, the battery and the network connection).
     • It provides a stable, consistent way for applications to deal with the hardware without having to know all the details of the hardware.

4. OS development

   • On the first computers, with no operating system, every program needed the full hardware specification to run correctly and perform standard tasks, and its own drivers for peripheral devices like printers and punched paper card readers. The growing complexity of hardware and application programs eventually made operating systems a necessity.
     • Early computers were built to perform a series of single tasks, like a calculator.In the 1940s, the earliest electronic digital systems had no operating systems.In the early 1950s, a computer could execute only one program at a time.Later machines came with libraries of programs, which would be linked to a user's program to assist in operations such as input and output and generating computer code from human-readable symbolic code. Operating systems did not exist in their modern and more complex forms until the early 1960s.

5. Example:

Bilder und Dateien der Mindmap