Windows 95

The "Start" button made its debut in Windows 95.

Windows 95 (originally code-named Chicago) is a hybrid 16-bit/32-bit graphical operating system released on August 24, 1995 by the Microsoft Corporation.

Windows 95 is a direct descendant of Microsoft's formerly separate MS-DOS and Windows products, the first in that line without any support for older, 16-bit x86 processors, thus requiring an Intel 80386 processor, or a compatible faster one, running in protected mode. It featured significant improvements to the GUI and underlying workings, and was the first Windows product to be tied to a particular version of DOS (Microsoft's DOS 7.0).

Some people argue that this way Microsoft were able to leverage the dominant position Windows 3.1x had established in the GUI market to ensure that no non-Microsoft product would be able to provide the underlying operating system services.

One should however ask oneself what kind of services a 16-bit, real-mode, single-tasking MS-DOS, knowing only uppercase 8.3 pathnames was still able to provide to Windows 95, which now had 256-character mixed-case long file names, preemptively multitasked protected-mode 32-bit applications and (since version 1.0) its own executable file formats.

With the introduction of 32-Bit File Access in Windows for Workgroups 3.11, which meant that 16-bit real mode MS-DOS was no more used for managing the files when Windows was running, and the earlier introduction of the 32-Bit Disk Access, which meant that PC BIOS was no more used for managing raw hard disks, MS-DOS and BIOS code has stopped playing a significant role while Windows was running. MS-DOS has been essentially reduced to the role of a boot loader for the protected-mode Windows kernel. It could still be used for running old-style drivers, for compatibility, but Microsoft discouraged using them, as this prevented proper multitasking and impaired system stability. The Control Panel allowed to see what MS-DOS components were still used by the system; optimial performance was achieved when they were all bypassed. Windows kernel still used MS-DOS drivers in the so-called Safe mode, but this mode existed merely to allow fixing problems with loading native, protected-mode drivers.

32-Bit File Access was a prequisite for the long file names feature introduced with Windows 95. It was available to both Windows programs and MS-DOS programs started from Windows (they had to be adapted slightly, since accessing long file names required using larger pathname buffers and hence different system calls). DOS-compatible competing operating systems needed at least an upgrade to be able to see these names. Using a non-aware version of DOS utilities to manipulate files from an MS-DOS window meant that the long names were not visible and would be lost if files were copied or moved around. During a Windows 95 automatic upgrade of an older Windows 3.1 system, DOS and third party disk utilities which could destroy long file names were identified and made unavailable.

Windows 95 played a dual-role. It brought significantly greater power and usability to the desktop GUI, and also ended competition in the desktop operating system market. While it was technically possible (but not a good idea given the above) to start the Windows 95 kernel and GUI from DR-DOS - and probably PC-DOS too - this did not emerge in court until some years later, by which time the other major players in the DOS market were effectively out of business. In the marketplace, Windows 95 was an unqualified success, and within a year or two of its release had become the most successful operating system ever made.

Windows 95 was released with great fanfare, including a commercial featuring the Rolling Stones song Start Me Up (a reference to the Start button). Microsoft's PR campaign featured stories of people queuing outside stores to get a copy, and there were tales of people without computers buying the software on hype alone, not even knowing what Windows was.

The release of Windows 95 coincided with a general movement of computing into the mainstream, largely fueled by a dramatic drop in hardware prices, in particular, by the end of Intel's long-held near-monopoly on CPU production with the entry of fast, low-cost parts from AMD and Cyrix.

Windows 95 marked the introduction of the "Start" button and taskbar to the desktop PC, which have remained staple features of all subsequent versions of Windows.

Later editions of Windows 95 (OSR 2, OSR 2.1, OSR 2.5) came with Internet Explorer 3, then Internet Explorer 4 preinstalled. Internet Explorer 4 introduced several changes to some aspects of the GUI when it was integrated into the operating system. Internet Explorer was then used to render the desktop and window contents using HTML. This was a focal point in Microsoft's antitrust lawsuit, as an integrated Explorer edged out competitor Netscape's product.

Windows 95 has been succeeded by Windows 98, Windows 98SE, Windows ME, Windows 2000 and Windows XP. The Windows NT-based kernel used in Windows 2000 and Windows XP has shown itself to be much more robust, and more powerful than its predecessor in Windows 95, Windows 98, and Windows ME. As a result, those versions of Windows are being phased out. As of December 31, 2002, Microsoft ended its support for Windows 95.