Early versions of Windows were pretty graphic user interfaces - desktops. This stemmed from the fact that they were run from the operating system MS-DOS and used the mechanisms in the field even file handling. On the other hand, even these early 16-bit operating environment had some features of a full operating system, such as having their own executable file format and their own device drivers (timer, display devices, printers, mouse, keyboard or sound generating devices) used by applications. Differently than was possible in MS-DOS, Windows overlays allow you to run multiple applications simultaneously, operating in the mode of cooperative multitasking. Another feature of the 16-bit Windows implementation was to use a complicated system of segmented virtual memory is supported in software, and this system enabled the application to run a size in excess of the amount of available computer memory. Segments of data were brought to the memory and removed from it, if only the free space has fallen dangerously. The data also underwent the movement, if the application does not require constant monitoring by the CPU, for example, waiting for the introduction of user data. The environment using this technology to Windows 1.0, released in 1985, and Windows 2.0 (year 1987), together with the associated environmental Windows/286.
Windows/386 introduced into the environment of the kernel for 32-bit protected mode CPU and monitor virtual machines. For the period of the session created an overlay of one or more virtual 8086 environments, enabling the virtualization of devices (video card, keyboard, mouse, timer and interrupt controller) for each of them. User-visible effect of this technology was the ability to run multiple environments, MS-DOS mode, multi-tasking to expropriation, each of which was run in a separate window (graphics applications MS-DOS required a transition to full screen mode). Applications designed for Windows was still running in multitasking mode, cooperative, and each was placed in a separate environment.
Environment Windows 3.0 (year of publication 1990) and Windows 3.1 (year 1992) significantly improved the above-described mechanisms, primarily through the use of virtual memory and are loaded virtual device drivers (VxD). which allowed individual DOS windows running in multitasking shared use of contractual devices. With these solutions, Windows applications can be run in 16-bit protected mode (both the Windows environment to work in standard mode and enhanced mode, processor 386) to give access to several megabytes of memory, were also exempt from having to use virtual memory system supported by software. Continue to operate in a common address space, where they were partially protected by the memory segment, and their execution is accomplished in a cooperative multitasking mode. For Windows 3.0, Microsoft also wrote in assembler part of the key features of the environment, reducing memory requirements and accelerated platform for its operation.
After an introduction to the Windows for Workgroups 3.11 32-bit file access, the Windows platform could eventually resign from the management of files by the DOS operating system. Using the features of the new mechanism, the Windows 95 operating system made it possible to use long file names, and their limitations DOS file names (8 characters plus 3 extension names) has been reduced to the role of the boot loader when the computer starts. Windows 95 and ME, the successor to version therefore had two nuclei, the environment: just after take-off run DOS, and a moment later, multi-tasking environment (desktop). DOS itself was supplied with Windows, making it (partially) handle long file names, if its applications were called from Windows. Microsoft's competitors do not accept these new heat. The most important feature of the new system was able to run 32-bit multi-threaded graphics programs operating in multitasking mode of expropriation. Unfortunately, the need to maintain backward compatibility with 16-bit programs meant that the GUI components were still 16-bit, this does not fully reentrant, which resulted in reduced system performance and stability of his troubles.
Windows 95 was released in three versions: the first one debuted in 1995 and another in 1996 and 1997. Two later versions were only available in the OEM editions, and one of the most important features are implemented in a FAT32 file system and correct operation of USB devices (version OSR2.1). Another product was a series of Windows 98, which appeared on the market twice - in 1998 and known as Windows 98 Second Edition a year later. In 2000 Microsoft released Windows Me (Me is a shortcut Millennium Edition), based on the code of Windows 98, but in matters of appearance is designed as Windows 2000. Another introduced in Windows Me System Restore was the option that allowed the user to restore the system settings for a specific day. It was not warmly welcomed the solution, because in many cases resulted in conflicts. Windows Me was adopted in the market as "filler" on the road to a full merger of the two branches developed by the Microsoft operating systems. Microsoft product but did not give sufficient time to "settle" on the market before it introduced Windows XP.
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