The very
first in the line of
IBM personal computers, and one of the first machines to use the
x86 architecture we all know and love (hah!)
today.
The original IBM PC was nothing special when it was released in the early 80s. It only had 16K of RAM, and two display choices: text-only monochrome or a much fuzzier CGA display that could display a maximum of four colors at a time. Even the Apple II, which was much criticized at the time for having mediocre graphics capability, could out-do the IBM PC. The PC also only shipped originally with 64K of RAM, and a single 5.25", 360K floppy drive.
Of course, in the business world, nobody cared about this. The simple fact that it was IBM ensured that the PC was quickly adopted and was purchased in the thousands by businesses. This led to individuals purchasing them because they used one at work. The real revolution, however, didn't happen until clone manufacturers came up with a clean-room version of the IBM PC BIOS, and started producing IBM PC clones. There was a lawsuit, but the clone makers won. As Intel produced faster and better processors, all backward compatible with the 8088, the x86 architecture gained a major foothold in the industry.
Backward compatibility has been strong throughout the PC legacy, however. A modern Pentium III 933 with half a gig of RAM can still run, in real mode (IE, without emulation), the software developed for the original IBM PC.