MS-DOS is 30 years old

He recently celebrated his birthday with MS-DOS.

MS-DOS was originally developed by Seattle Computer Products (SCP) as QDOS (Quick and Dirty Operating System). It was eventually marketed as 86-DOS (because it was designed for Intel 8086 processors). Due to certain events - which gave rise to several legends - QDOS was licensed by Microsoft to IBM on behalf of SCP. Microsoft bought the system from SCP for $ 50 shortly before the PC came out, later the deal meant millions to it and laid the groundwork for its proliferation.

Both IBM and Microsoft have released their own versions of DOS. Originally, IBM only inspected and packaged Microsoft products, so IBM versions appeared shortly after Microsoft's. However, MS-DOS 4.0 was actually based on IBM PC-DOS 4.0, because at the time, Microsoft was focusing on developing OS / 2. Microsoft marketed versions of DOS under the name “MS-DOS” and IBM as “PC DOS”. Initially, when Microsoft licensed an OEM version of MS-DOS to a computer company, the manufacturer could change the name of the operating system (e.g., TandyDOS, Compaq DOS). Most of these versions were completely identical to MS-DOS. After a while, Microsoft began to insist that manufacturers keep the MS-DOS product name. In the end, only IBM opposed this claim.    

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MS-DOS has evolved at a very rapid pace, borrowing several significant capabilities from other products and operating systems, such as Microsoft's own Xenix (a Unix variant) and Digital Research's DR-DOS, as well as utilities such as Norton Utilities , PC Tools (Microsoft Anti-Virus), QEMM Extended Memory Manager, Stacker Disk Compressor, and more.    

With the advent of the Intel 80286 microprocessor, IBM and Microsoft began work on a joint project called OS / 2, which would originally have been a protected-mode version of MS-DOS. Later, Microsoft exited the project to devote all of its resources to Windows and Windows NT. Digital Research has developed a graphical user interface (GUI) called GEM, which did not spread on PCs, although it was very popular on Atari ST machines. With the release of Microsoft Windows 3.0, this system was completely forgotten.

Source: wikipedia