The Computer History Museum (CHM) announced today that it has, with permission from Microsoft Corporation, made available original source code for two historic programs: MS-DOS, the 1982 "Disk Operating System" for IBM-compatible personal computers, and Word for Windows, the 1990 Windows-based version of their word processor.
MS-DOS was basically a file manager and a simple program loader. The user interface was text commands typed on a keyboard, followed by text responses displayed on the screen. There was no graphical output, and no mouse for input. Only one user application program could run at a time. File names were limited to 8 characters, plus a 3-character extension indicating the file type. There were commands like “dir” to list the files in a directory, and “del” to delete a file; you ran a program by typing the name of its executable file.
It may have been a “small program” but it had some sophisticated features, including support for style sheets, multiple windows, footnotes, mail-merge, undo, and the proportional fonts that the newly emerging laser printers would be able to use.
The first version for Microsoft Windows was released in late 1989 at a single-user price of $495. It received a glowing review in Inforworld  that didn’t flinch at the price: “If your system is powerful enough to support Microsoft Windows, at $495 it is an excellent value.”
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