NEW YORK (AP) — With Friday’s release of the touch-centric Windows 8 software, Microsoft continues more than three decades of making operating systems for personal computers.

Microsoft Corp. got its start on PCs in 1981 through a partnership with IBM Corp. Microsoft made the software that ran IBM’s hardware, and later machines made by other manufacturers. That first operating system was called MS-DOS and required people to type instructions to complete tasks such as running programs and deleting files.