Microsoft Windows

Often simply called Windows, Microsoft Windows is a family of proprietary operating systems. Windows PCs run Intel or Intel-compatible microprocessors and use IBM-compatible hardware architecture. It originated in 1981 as an add-on to the older MS-DOS operating system for the IBM PC, which was command-line driven. Released in 1985 (Windows 1.0), Microsoft struggled to improve Windows through the rest of the 1980s.

Windows called NT (New Technology) was first released in 1993. NT, which progressed through several versions, was targeted at the high-end server market, while the consumer version of Windows continued to evolve incrementally as Windows 95 and Windows 98 (released in those respective years). These versions included improved support for networking (including TCP/IP, the Internet standard) and a feature called “plug and play” that allowed automatic installation of drivers for new hardware.

Toward the end of the century, Microsoft began to merge the consumer and server versions of Windows. Windows 2000 incorporated some NT features and provided somewhat greater security and stability for consumers. With Windows XP, released in 2001, the separate consumer and NT versions of Windows disappeared entirely, to be replaced by home and “professional’ versions of XP.

Windows XP supports multiple operating environments and symmetric multiprocessing. The use of kernel objects to provide basic services, along with support for client-server computing, enables Windows XP to support a wide variety of application environments. It provides virtual memory, integrated caching, and preemptive scheduling. Windows XP supports a security model stronger than those of previous Microsoft operating systems and includes internationalization features.

Introduced in early 2007, Microsoft Windows Vista includes a number of new features, including a 3D user interface (“Aero”), easier and more robust networking, built-in multimedia capabilities (such as photo management and DVD authoring), improved file navigation and desktop search. Perhaps the most important feature is enhanced security, including User Account Control, which halts suspect programs and requests permission for them to continue.

Windows 7 was released to manufacturing on July 22, 2009. Unlike its predecessor, Windows 7 was intended to be a more focused, incremental upgrade to the Windows line. Presentations given by Microsoft in 2008 focused on multi-touch support, a redesigned Windows Shell with a new taskbar, referred to as the Superbar, a home networking system called HomeGroup and performance improvements.

Windows 8, which was released to manufacturing on August 1, 2012, introduced major changes to the operating system’s platform and user interface to improve its user experience on tablets, where Windows was now competing with mobile operating systems. These changes included a touch-optimized Windows shell, the Start screen (which displays programs and dynamically updated content on a grid of tiles), a new platform for developing apps with an emphasis on a touchscreen input, integration with Microsoft SmartScreen phishing filtering service.

From the user’s point of view, Windows is a way to control and view what is going on with the computer. The user interface consists of a standard set of objects (windows, menus, buttons sliders, and so on) that behave in generally consistent way. This consistency reduces the learning curve for mastering a new application.

Windows includes a number of features designed to make it easier for users to control their PC. Most settings can be specified through windows called dialog boxes, which include buttons, check boxes or other controls.

From the programmer’s point of view, Windows is a multitasked, event-driven environment. Responsible programs allocate no more memory than they need, and release memory as soon as it is no longer needed. If the pool of free memory becomes too low, Windows starts swapping the least recently used segments of memory to the hard drive. This scheme, called virtual memory, allows a PC to run more and larger programs than would otherwise be possible.

While Windows still remains the dominant PC operating system with tens of thousands of applications and at least several hundred million users around the world, it is likely that the PC operating systems of 2020 will be as different from today’s Windows as the latter is from the MSDOS of the early 1980s

UNIX/Linux

By the 1970s, time-sharing computer systems were in use at many universities and engineering and research organizations. Such systems required a new kind of operating system that could manage the resources for each user as well as the running of multiple programs. An elaborate project called MULTICS had been begun in the 1960s in an attempt to create such an operating system. However, as the project began to bog down, two of its participants, Ken Thompson and Dennis Ritchie decided to create a simple, more practical operating system for their PDP-7. The result would become UNIX.

The essential core of the UNIX system is the kernel, which provides facilities to organize and access files, move data to and from devices, and control the running of programs. In designing UNIX, Thompson deliberately kept the kernel small, noting that he wanted maximum flexibility for users.

A UNIX system typically has many users, each of whom may be running a number of programs. The interface that processes user commands is called the shell. It is important to note that in UNIX a shell is just another program, so there can be (and are) many different shells reflecting varying tastes and purposes. Traditional UNIX shells include the Bourne shell (sh), C shell (csh), and Korn shell (ksh). Modern UNIX systems can also have graphical user interfaces similar to those found on Windows and Macintosh personal computers.

The versatility of UNIX quickly made it the operating system of choice for many most campuses and laboratories, as well as for many software developers.

Although UNIX has been somewhat overshadowed by its Linux progeny, a variety of open-source versions of traditional UNIX systems have become available. In 2005 Sun Microsystems released OpenSolaris (based on UNIX system V). There is also OpenBSD, derived from the UC Berkeley Software Distribution (but with stronger security features) and available for most major platforms. Finally, the continuing influence of UNIX can also be seen in the current generation of operating systems for Apple Macintosh (OS X).

LINUX is an increasingly popular alternative to proprietary operating systems. Its development sprang from two sources. First was the creation of open-source versions of UNIX utilities by maverick programmer Richard Stallman as part of the GNU project during the 1980s. Starting in 1991, another creative programmer, Linus Torvalds, began to release open-source versions of the UNIX kernel. The combination of the kernel and utilities became known as Linux (a combination of Linus and UNIX).

As an open-source product, LINUX is continually being developed by a community of thousands of loosely organized programmers.

LINUX is very versatile and probably runs on more kinds of devices than any other operating system. These include supercomputer clusters, Web and file servers, desktops (including PCs designed for Windows and Macs), laptops, PDAs, and even a few smart phones.

A Linux distribution such as UBUNTU is now a viable alternative to Windows unless one has to use certain programs that do not have Linux versions. However, such options as dual-booting, emulation, or virtual machines offer the ability to use both LINUX and Windows on the same machine.

OS X

Jaguar, panther, tiger, and leopard - these and other names of sleek big cats represent versions of Apple’s Macintosh operating system, OS X (pronounced “OS 10”). Unlike the previous Mac OS, OS X, while broadly maintaining Apple’s user interface style, is based on a version of UNIX called OpenStep developed by NeXT starting in the 1980s.

At the core of OS X is a free and open-source version of UNIX called ‘Darwin”, with a kernel XNU. On top of this Apple built a distinctive and subtly colorful user interface called Aqua and a new version of the Macintosh Finder file and program management system.

OS X introduced a number of new capabilities to provide a more stable and reliable platform than its predecessor, Mac OS 9. For example, pre-emptive multitasking and memory protection improved the system’s ability to run multiple applications simultaneously without them interrupting or corrupting each other.

Notes:

TCP/IP - Transmission Control Protocol/Internet Protocol - на­бор сетевых протоколов передачи данных

“Plug and Play” - принцип «подключи и работай»

User Account Control - контроль учетной записи пользова­теля

Superbar - «суперпанель» задач в Windows7

Phishing - (от fishing-рыбная ловля, выуживание)- вид ин­тернет-мошенничества, целью которого является получе­ние доступа к конфиденциальным данным пользователей - логинам и паролям.

PDP-7 - миникомпьютер, производившийся Digital Equipment Corporation (1965г.)

OpenBSD (Berkeley Software Distribution) - свободная мно­гоплатформенная операционная система, основанная на BSD- реализации UNIX-системы

GNU - рекурсивное сокращение фразы “GNU is Not UNIX”-свободна операционная система типа UNIX

PDA - Personal Digital Assistant- карманный персональный компьютер (КПК)

UBUNTU - (от зулу ubuntu –“человечность”)- операционная система, основанная на Debian GNU/Linux.

XNU - акроним англ. “X is Not UNIX”- ядро операционных систем, используемое в ОС семейства OS X