Microsoft has announced that it has partnered with History Museum to preserve the source code of the early versions of MS-DOS and Word for Windows for making it public. This is part of an continuous effort by History Museum to preserve the source code of the earliest computer software and then make this source code accessible to general public.
Microsoft developed MS-DOS after it was approached by IBM to develop an OS for it. Microsoft ended up developing two versions: PC-DOS for IBM and MS-DOS for other computer manufacturers. The first Word for Windows was released in 1989 and with a short period of four years totally dominated half of the word processing software market.
Tech companies are often not forthcoming in making public the source code of any of their software and it has taken years of discussions between Microsoft and History museum to reach this agreement.