 Historically, for example, Adobe's portable document format (PDF) did not succeed until Adobe priced the PDF reader at zero, substantially increasing sales of PDF writers.In the operating systems market for home computers, created in the early 1980s with the introduction of the Macintosh and IBM PC, Microsoft decided to steeply discount the software development toolkit (SDKs) for its operating system, relative to Apple pricing at that time, lowering the barrier to entry to the home computer market for software businesses.This resulted in a big increase in the number of applications being developed for home computers, with the Microsoft Windows/IBM PC being the operating system/computer type combination of choice for both software businesses and software users.