Quarterdeck Corporation of Santa Monica, California (now owned by Symantec) was the inventor of the key memory-management code that allows a computer to switch from "real mode" to "protected mode." The innovation allowed for memory remapping, program swapping, and large applications to run on personal computers.

Without this ingenious programming step, all Intel-based DOS PCs would have been limited to a few tiny text-base programs running on a DOS screen. In other words, Windows could not exist.

How did Microsoft treat potential competitor Quarterdeck? Microsoft used the step in its own memory tool for DOS. Then Microsoft apparently rigged Windows so that it would become unstable if a directory called "QEMM" existed on a PC hard drive.

"QEMM" was Quarterdeck's flagship product and income source. Microsoft, many believe, also attempted to mislead Quarterdeck by claiming that the smaller company should develop a new GUI that would ride on top of Windows95, which Quarterdeck could then sell to PC makers for preload purposes.

However, Microsoft had already made contracts with PC makers forbidding them to load any such GUI. Apparently, Microsoft's intent was to have Quarterdeck waste time and resources developing a product that Microsoft had already banned from the market. Of course that tactic shows clearly that the PC market is not really a free market. Microsoft can ban any competing software through contracts, predatory program design -- or both.

STAC Electronics developed a hard-disk compression scheme that allowed PCs to store 1.5 to 2.5 as much data on a hard drive. Even today, this would be quite useful for notebook PCs and embedded systems. However, Microsoft copied this code and embedded it into MSDOS 6.0 as "DoubleSpace." Microsoft was found liable in civil court and later paid $83 million in damages, according to reports on the case. But very few companies have the resources that STAC did to fight for years for their legal rights against giant, well-financed Microsoft's legal steamroller.

Tiny company Go Corp. invented pen-based computing in the early 1990s. When invited to consider selling its technology to Microsoft, Go gladly agreed to have a "marketing guy" from Microsoft examine the product. Instead, several Microsoft programmers -- who many say were pretending to be marketers -- spent three days poring over every detail of the source code for Go's flagship product.

Then they pronounced it a dud and left town. Six months later, Microsoft began offering a similar product using Go's approach -- and dared Go to sue them. Next thing you know, Go went bankrupt and disappeared.