Today's non-Mac personal computer is, essentially, an IBM PC. The Intel-based, Windows-running computers that have dominated the market since the 1990s were born from the IBM PC, which was released in 1981 with a humble 4.77 MHz Intel 8088 processor and 16KB of RAM. IBM Model 5150 wasn't the company's first effort to move into the personal computer market -- they'd released an expensive PC back in 1975 -- but it was the one that did everything right. The system wasn't the fastest around, but it was equipped with Intel's 16-bit processor, rather than the older 8-bit processors most computers at the time were using. Despite being a new chip, the 8088 used an 8-bit bus, making it compatible with existing peripherals and memory expansions [source: Reimer].
The IBM PC cost about $1600 in a base configuration, which was affordable for a powerful computer at the time. The system was popular, and software was coded specifically to take advantage of IBM's design and maximize the Intel 8088's performance. So, other companies cloned IBM's BIOS and put out IBM PC clones.
Within a few years, all x86 computers -- those using Intel's processors -- were compatible with the IBM PC and virtually identical to IBM's design. They all ran MS-DOS, and the x86 PC field went on to become the de facto standard. There's only one reason the IBM PC isn't the most popular computer ever made -- too many other companies made their own versions!