Operating System

In the realm of computers, operating systems (OS) play a crucial role in managing both hardware and software resources. This article aims to provide a beginner-friendly exploration of operating systems, shedding light on their functions, types, and historical evolution.

Operating System: An operating system is like the brain of a computer, coordinating various tasks, managing resources, and providing services for computer programs. It serves as an intermediary between application software and computer hardware, ensuring smooth communication and efficient utilisation of resources.

Key Functions of Operating Systems:

• Task Scheduling:

1. Optimising System Usage: Time-sharing operating systems are designed to efficiently allocate tasks, ensuring optimal utilisation of system resources. This function is crucial in multi-user environments, allowing multiple tasks to run concurrently without compromising performance.
2. Resource Usage Tracking: Operating systems employ accounting software to monitor and track resource usage. This aids in cost allocation by providing insights into how resources are utilised, essential for organisations managing computing infrastructure.

• Resource Management:

1. Mediator for Input/Output and Memory Allocation: OS serves as a mediator between applications and hardware, facilitating seamless input/output operations and managing memory allocation. This ensures that each program receives the necessary resources for efficient execution.
2. Interaction with Hardware: Operating systems interact directly with hardware components, executing application code and handling system calls. This interaction is vital for maintaining system stability and responsiveness.

• Device Interaction:

Communication Management: Operating systems are responsible for managing communication between software programs and various hardware components. This includes handling input from peripherals and ensuring proper output to display devices.

Operating System Market Share (As of September 2023):

• Personal Computers:

1. Microsoft Windows Dominance: Microsoft Windows continues to dominate the personal computer market with an impressive 68% market share. Known for its user-friendly interface and widespread compatibility, Windows remains a popular choice among users.
2. macOS by Apple Inc.: Apple’s macOS secures the second position with a 20% market share. Renowned for its sleek design and seamless integration with Apple hardware, macOS caters to a dedicated user base.
3. Linux Varieties: Linux, including ChromeOS, collectively holds a 7% market share. While it may have a smaller share, Linux is celebrated for its open-source nature and robust security features.

• Mobile Devices:

1. Android Dominance: Android maintains its lead in the mobile device market with an impressive 68.92% share. Known for its versatility and extensive app ecosystem, Android powers a wide range of smartphones and tablets.
2. Apple’s iOS and iPadOS: Apple’s mobile operating systems, iOS and iPadOS, follow with a 30.42% market share. Recognized for their seamless integration with Apple devices and emphasis on user privacy, iOS and iPadOS cater to a loyal user base.
3. Other Operating Systems: The remaining 0.6% of the market is shared among various other operating systems. While these may have a smaller presence, they contribute to the diverse landscape of mobile operating systems.

Types of Operating Systems:

• Single-tasking vs. Multitasking:

1. Single-tasking: This type allows the execution of only one program at a time, making it suitable for simple computing tasks.
2. Multi-tasking: Operating systems in this category enable the concurrent execution of multiple programs. It can be further classified into preemptive (where the OS manages CPU time) or cooperative (where tasks collaborate to share processing time).

• Single-user vs. Multi-user:

1. Single-user systems: These systems support the execution of multiple programs but lack user distinction, making them suitable for personal use.
2. Multi-user systems: In contrast, multi-user systems accommodate simultaneous interactions from multiple users, commonly employed in networked environments.

• Distributed Operating Systems:

These OS manage a network of computers, presenting them as a unified and cohesive unit. This facilitates seamless communication and resource sharing among the interconnected devices.

• Embedded Operating Systems:

Tailored for small, autonomous devices such as PDAs, embedded operating systems like Windows CE and Minix 3 provide the necessary functionality within constrained environments.

• Real-time Operating Systems:

Critical for time-sensitive applications, real-time operating systems guarantee timely processing of events or data. They find applications in areas where precision and timing are paramount.

• Library Operating Systems:

Functioning as modular entities, library operating systems offer OS services as libraries. These libraries can be utilised to construct specialised and deployable images tailored to specific requirements.

History of Operating Systems:

• Early Developments (1950s): The genesis of operating systems dates back to the 1950s when basic features began to emerge, evolving from the rudimentary functions of resident monitors. During this era, early computers primarily executed single tasks and lacked the intricate complexities of modern operating systems.
• Mainframes Era (1960s): In the 1960s, IBM’s OS/360 revolutionised the landscape by introducing the concept of a single operating system spanning an entire product line. Concurrently, CP-67 pioneered the idea of virtual machines on IBM mainframes, laying the foundation for more versatile and efficient computing environments.
• Microcomputers and Personal Computers: As technology progressed, microcomputers became prevalent, necessitating the development of minimalistic operating systems. CP/M and MS-DOS emerged as pioneers in this realm, providing the necessary framework for microcomputer operations. In the 1980s, Apple’s Macintosh marked a milestone by introducing a user-friendly graphical user interface (GUI), significantly enhancing the user experience.
• Modern Era (1990s): The advent of the Intel 80386 processor in the late 1980s enabled the development of multitasking operating systems, allowing computers to perform multiple functions simultaneously. Notable developments in the 1990s include the introduction of Windows NT and Linux, both of which played pivotal roles in shaping the modern operating system landscape.
• Open Source Movement: The GNU Project, initiated with the goal of creating a free UNIX replacement, gained prominence in the realm of open-source software. In 1991, Linus Torvalds introduced Linux, a Unix-like kernel. When combined with GNU components, Linux formed a complete and robust operating system, showcasing the power and potential of open-source collaboration.

Components of an Operating System

• Kernel: At the heart of an operating system is the kernel, which acts as the intermediary between application software and computer hardware. Utilising firmware and device drivers, the kernel exercises fundamental control over hardware devices, managing memory access, determining resource allocation for programs, optimising CPU operating states, and organising data storage on media like disks, tapes, and flash memory.
• Program Execution: The operating system provides an interface for application programs to interact with computer hardware. When an application is executed, the operating system kernel creates a process, allocates memory space and resources, sets CPU operating states, loads program code into memory, and initiates program execution. In multitasking systems, priorities are assigned to processes to ensure optimal operation.
• Interrupts: Interrupts provide an efficient mechanism for operating systems to respond to external events. These events, known as interrupts, cause the CPU to shift control from the current program to an interrupt handler or interrupt service routine (ISR). The operating system must manage the transfer of control to the ISR, save the current process state, and restore it after the interrupt is serviced.
• Software Interrupts: Software interrupts are messages signalling events to a process. They can occur due to expected events, such as time slices or user input like pressing Control-C in a command-line environment. Additionally, software interrupts may be triggered by error conditions, like division by zero or accessing an invalid memory address.
• Signals: In Unix-like operating systems, signals are a form of software interrupts. They inform processes about asynchronous events, such as normal process completion, error exceptions, resource depletion, and more. Signals play a vital role in coordinating communication between processes, especially in scenarios like piping in command-line environments.
• Hardware Interrupts: To enhance efficiency, I/O devices use hardware interrupts to signal the completion of operations, eliminating the need for CPU polling. This ensures that the CPU does not need to wait for each I/O operation to finish, enhancing overall system performance. Direct memory access (DMA) is another mechanism that allows devices to bypass the CPU for data transfer.
• Input/Output (I/O): Interrupt-driven I/O is a mechanism where each keystroke or mouse movement generates an interrupt, allowing immediate interaction with the computer. For devices with high data transfer rates, like hard disk drives, direct memory access (DMA) enables data transfer between the device and memory without CPU intervention, reducing processing overhead.
• Modes: Modern CPUs support multiple modes, such as user mode and supervisor mode. Supervisor mode grants unrestricted access to all machine resources, allowing the kernel to perform low-level tasks, while user mode imposes restrictions on instruction use and resource access. The switch between these modes is crucial for maintaining system stability and security.
• Memory Management: The operating system oversees memory management, allocating and deallocating memory for processes. It ensures that processes operate within their designated memory space, preventing unauthorised access or disruptions. Memory management is vital for maintaining system stability and preventing conflicts between running processes.