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themselves by a lower price, increased portability, or better performance. In
time, IBM lost its dominant position in the PC market. It is now one of many
companies producing IBM PC-compatible computers.
IBM never produced an operating system for its PCsȌthat is, the software that
organizes the interaction between the user and the computer, starts application
programs, and manages disk storage and other resources. Instead, IBM offered
customers the option of three separate operating syst
ems. Most customers
couldn't care less about the operating system. They
chose the system that was
able to launch most of the few applications that existed at the time. It happened
to be DOS (Disk Operating System) by Microsoft. Microsoft cheerfully licensed
the same operating system to other hardware vendors and encouraged software
companies to write DOS applications. A huge number of useful application
programs for PC-compatible machines was the result.
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The VisiCalc Spreadsheet Running on an Apple II
