Original sentence: Apple has relied on two companies for its microprocessor chips and in neither case was there anywhere else to turn when they could not apparently deliver.Based on Apple's saying, IBM's failure to deliver a faster PPC chip is the main cause of the switch.However, Apple's lower-single-digit marketshare in the personal computer business also implies that Apple could not buy enough chips to support Macintosh-oriented R&D for newer PPC chips
Edited sentence: Apple has relied on two companies for its microprocessor chips and in neither case was there  anywhere else to turn when they could not apparently deliver