Back in the ancient days before the comment "Drop to command prompt" made sense as the command prompt a little known company called Microsoft bought QDOS and renamed it as MS DOS.  That was also back when IBM was the be all and end all of 8086 (and 8080) processors and planned for their newly designed Personal Computer to run an OS called CP/M-86 but couldn’t get a good enough deal on the licensing; which lead to Microsoft’s product being adopted.  It also lead to the Personal Computer catching on much more quickly and thoroughly than anyone predicted.

From that humble beginning came what was first used to slow your 386DX based computer enough to be able to control Wing Commander and now controls almost 90% of the PCs currently running and keeps techs employed world wide.. 

"Thirty years ago, on July 27 1981, Microsoft bought the rights for QDOS (Quick and Dirty Operating System) from Seattle Computer Products (SCP) for $25,000. QDOS, otherwise known as 86-DOS, was designed by SCP to run on the Intel 8086 processor, and was originally thrown together in just two months for a 0.1 release in 1980."

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