An Overview of Operating Systems
The first operating system that looked like modern operating systems was UNIX, which Bell Labs created in 1969.
An operating system is a piece of software program.
It acts as an intermediary between the user of a computer and computer hardware and facilitates an environment in which a user can execute programs conveniently and efficiently without much difficulty while managing resources without conflicting with each other.
It typically operate in two distinct modes: kernel mode and user mode. The kernel mode has higher privileges and controls hardware directly, while the user mode is where application programs run. Separating these modes enhances system stability and security.
It is responsible for resource allocation and management. This includes memory allocation for programs, scheduling processes to use the CPU efficiently, managing input and output devices, and handling file storage and retrieval. In addition to those, the operating system provides services to applications, such as communication between processes, error handling, and security controls.
Operating systems implement security measures to protect the integrity of data and the privacy of users. This includes user authentication, access control, and data encryption.
Operating systems have evolved over time and come in various forms, including Windows, macOS, Linux (widely used in servers), Unix (The oldest, Modern Popular OS's inspired by this), and mobile operating systems like Android and iOS. Each has its own unique features and capabilities.
The operating system always runs in the background, even when no user applications are actively using the computer. It ensures that the system is ready to execute programs as needed.
It requires regular maintenance and updates to fix bugs, enhance performance, and provide new features. Users and administrators need to keep their operating systems up-to-date for security and stability.
It also performs basic tasks such as recognizing input from the keyboard, keeping track of files and directories on the disk, sending output to the display screen and controlling peripheral devices.
The core of the operating system is a kernel, which manages critical system functionalities.
Functions of OS
Convenience: An OS makes a computer more convenient to use.
Efficiency: An OS allows the computer system resources to be used efficiently.
Ability to Evolve: An OS should be constructed in such a way as to permit the effective development, testing and introduction of new system functions at the same time without interfering with service.
Proper Operation: The hardware must provide appropriate mechanisms to ensure the correct operation of the computer system and to prevent user programs from interfering with the proper operation of the system.
It's important to note that an operating system is composed of other various components, including:
Scheduler: Responsible for determining which processes should run and for how long, optimizing CPU usage.
Memory Management: Ensures efficient allocation and protection of memory for processes.
I/O Management: Controls input and output operations, allowing programs to interact with devices.
File System: Manages the storage and retrieval of data on storage devices.
The entities in and around the OS
System and application programs
Every general-purpose computer consists of the hardware to run the operating system, wherein we run system programs and application programs.
The hardware consists of memory, CPU, ALU, I/O devices, peripheral devices, and storage devices.
The system program consists of compilers, loaders, editors, OS, etc. The application program consists of any installed programs.
Reading something from a keyboard and writing to a file using methods available in programming languages are powered by OS which directly triggers internal system functions using system calls.
Central Processing Unit
CPU inherently reads data from the RAM effectively, where data fetches into the RAM from different sources. Because the CPU does not directly talk to other devices/parts such as the keyboard, mouse, disk, etc.
Control Unit - The control unit in a CPU manages instruction execution and data flow within the CPU.
Arithmetic Logic Unit - Performs Logical/Mathematical Operations.
Memory Unit - RAM.
Types of Resources for OS
Hardware Resources: Keyboard, Mouse, Printer, Monitor, LAN, WiFi, Hard disk, CPU, RAM, Touch, etc.
Software Resources: Pipes, Signals, Semaphores, etc
Do you know what happens when powering up your PC?
Turning On the Computer: When you press the power button, your computer starts waking up from a deep sleep.
Checking Everything: The computer's brain called the BIOS or UEFI, checks if all the parts inside are working correctly.
Finding the Start Button: It looks for the place where the computer's "start" button is, like your hard drive.
Booting Up: Next, it calls upon a small program called the "bootloader" to start the operating system.
Choosing the System: The bootloader might ask you which computer "system" (like Windows or macOS) you want to use if you have more than one.
Loading the Heart: Once you choose, it loads the main part of the system called the "kernel." This is the heart of your computer's brain.
Saying Hello: The kernel wakes up all the parts inside your computer, like the keyboard, mouse, and screen.
Ready for You: Finally, your computer is ready for you to use. You might see a picture with icons, or if you're on a computer with just words, you'll see a "command line."
Using Programs: You can open programs, like your web browser or word processor, to do things on your computer.
Managing Files: You can also work with files, like pictures or documents. The computer helps you keep them organized.
Connecting Online: If you want to use the internet, the computer helps you get online and visit websites.
Turning Off or Restarting: When you're done, you can turn off or restart your computer. It's like putting it to sleep until next time.
This way, your computer wakes up, gets ready for you, and helps you do all sorts of things, all credits to OS.!