Linux
Linux is a true 32-bit
operating system that runs on a variety of different
platforms, including Intel, Sparc, Alpha, and
Power-PC (on some of these platforms, such as
Alpha, Linux is actually 64-bit). There are other
ports available as well, but I do not have any
experience with them. Linux was first developed
back in the early 1990s, by a young Finnish then-university
student named Linus Torvalds. Linus had a "state-of-the-art"
386 box at home and decided to write an alternative
to the 286-based Minix system (a small unix-like
implementation primarily used in operating systems
classes), to take advantage of the extra instruction
set available on the then-new chip, and began
to write a small bare-bones kernel.
Eventually he announced
his little project in the USENET group comp.os.minix,
asking for interested parties to take a look and
perhaps contribute to the project. The results
have been phenomenal!