“But Unix had a serious shortcoming: No common version existed. Over the years different versions of Unix had proliferated like weeds, so that an application written for one would not run unmodified on another. While DOS presented a single target to consumers, applications writers and computer makers, Unix did not.”

“But Unix had a serious shortcoming: No common version existed. Over the years different versions of Unix had proliferated like weeds, so that an application written for one would not run unmodified on another. While DOS presented a single target to consumers, applications writers and computer makers, Unix did not.”

— G. Pascal Zachary