The IBMInternational Business Machines — a major computer and enterprise technology company since the early 20th century. PCPersonal computer — a computer designed for individual use, especially desktop or laptop machines. used off-the-shelf parts (Intel 8088, DOSDisk Operating System — an OS centered on disk storage; often refers to MS-DOS on PCs. from MSMicrosoft — the software company behind Windows, Office, and many developer tools.) and published expansion specs — clones from Compaq and others followed. Developers wrote business software once and sold it to an entire industry. The "PCPersonal computer — a computer designed for individual use, especially desktop or laptop machines." in "PCPersonal computer — a computer designed for individual use, especially desktop or laptop machines. programmer" means this machine and its descendants.

The IBMInternational Business Machines — a major computer and enterprise technology company since the early 20th century. PCPersonal computer — a computer designed for individual use, especially desktop or laptop machines. made the x86Intel's dominant CPU architecture family — the instruction set behind most PCs and servers for decades. + DOSDisk Operating System — an OS centered on disk storage; often refers to MS-DOS on PCs. platform the default for business and home computing worldwide.

Open expansion and clone compatibility created the largest software market in computing history.