Modern Operating Systems

In our day to day lives, we all tend to carry out a series of tasks. In most instances, these tasks are repetitive and can therefore be scheduled. With the help of electronic machinery, the level of productivity has exponentially increased over the years. These electronic components reduced a lot of excess labor but to improve productivity an additional level these tasks need to be automated. As a result, software implementation becomes an integral part in the actual hardware’s performance and design specification. Hardware can do only so much, but with well-designed software, a box of metal can perform complicated tasks such as real-time object detection to help identify a target or multiple targets in a crowd. Operating systems are used to help manage and execute these tasks.

One of the operating system's main tasks is to control the computer's resources—both the hardware and the software. The operating system allocates resources as necessary to ensure that each application receives the appropriate amount. In addition to resource allocation, operating systems provide a consistent application interface so that all applications use the hardware in the same way. This is particularly important if more than one type of computer uses the operating system or if the computer's hardware is likely to change. By having a consistent application program interface (API), software written on one computer and can run on other types of computers. Developers face the challenge of keeping the operating system flexible enough to control hardware from the thousands of different computer manufacturers.

Operating systems have to accomplish five main tasks; processor management, memory storage/management, device management, application interface, and also user interface. The operating system needs to allocate enough of the processor's time to each process and application so that they can run as efficiently as possible. This is particularly important for multitasking. When the user has multiple applications and processes running, it is up to the operating system to ensure that the device has enough resources to run properly. The operating system also needs to ensure that each process has enough memory to execute the process, while also ensuring that one process does not use the memory allocated to another process. This must also be done in the most efficient manner.

A computer has four general types of memory. In order of speed, they are: high-speed cache, main memory, secondary memory, and disk storage. The operating system must balance the needs of each process with the different types of memory available. Most computers have additional hardware, such as printers and scanners, connected to them. These devices require drivers, or special programs that translate the electrical signals sent from the operating system or application program to the hardware device. The operating system manages the input to and output from the computer. It often assigns high-priority blocks to drivers so that the hardware can be released and available for the next use as soon as possible.

Programmers use application program interfaces (APIs) to control the computer and operating system. As software developers write applications, they can insert these API functions in their programs. As the operating system encounters these API functions, it takes the desired action, so the programmer does not need to know the details of controlling the hardware. The user interface on the other hand, sits as a layer above the operating system. It is the part of the application through which the user interacts with the application. Some operating systems, such as Microsoft Windows and Apple Macintosh, use graphical user interfaces. Other operating systems, such as Unix, use shells. In theory, there are six different classes of operating systems: single and multi-tasking, single and multi-user, distributed, templated, embedded, real-time, and library. A single-tasking system can only run one program at a time, while a multi-tasking operating system allows more than one program to be running in concurrency. This is achieved by time-sharing. Time-sharing divides the available processor time between multiple processes that are each interrupted repeatedly in time slices by a task-scheduling subsystem of the operating system.

Multi-tasking may be characterized in preemptive and co-operative types. In preemptive multitasking, the operating system slices the CPU time and dedicates a slot to each of the programs. Unix-like operating systems, e.g., Solaris, Linux, as well as AmigaOS support preemptive multitasking. Single-user operating systems are defined by the name itself. These operating systems have no facilities to distinguish users, but may allow multiple programs to run in tandem. [1] A multi-user operating system extends the basic concept of multi-tasking with facilities that identify processes and resources, such as disk space, belonging to multiple users, and the system permits multiple users to interact with the system at the same time. Time-sharing operating systems schedule tasks for efficient use of the system and may also include accounting software for cost allocation of processor time, mass storage, printing, and other resources to multiple users.

A distributed operating system manages a group of distinct computers and makes them appear to be a single computer. The development of networked computers that could be linked and communicate with each other gave rise to distributed computing. Distributed computations are carried out on more than one machine. When computers in a group work in cooperation, they form a distributed system. [2] In an OS, 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. [3]

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. Windows CE and Minix 3 are some examples of embedded operating systems. A real-time operating system is an operating system that guarantees to process events or data by a specific moment in time. A real-time operating system may be single- or multi-tasking, but when multitasking, it uses specialized scheduling algorithms so that a deterministic nature of behavior is achieved. An event-driven system switches between tasks based on their priorities or external events while time-sharing operating systems switch tasks based on clock interrupts A library operating system is one in which the services that a typical operating system provides, such as networking, are provided in the form of libraries and composed with the application and configuration code to construct a unikernel: a specialized, single address space, machine image that can be deployed to cloud or embedded environments.

Now, Android is considered to be a mobile operating system. Developed by Google, this operating system is based on the Linux kernel and is designed primarily for touchscreen mobile devices such as smartphones and tablets. In recent years, Google has taken additional steps to further develop the Android operating system for televisions, wrist watches, game consoles, digital cameras, and even cars. This operating system was originally developed by Android Inc., which was bought by Google in 2005. Its first commercial Android device was launched in September 2008. Since then, the operating system has gone through a number of major releases. Each consecutive iteration of the operating system came with a number improvements and many new features. As of now, the most current version is 8.1 “Oreo”, and it was released in December 2017.