A CPU resarch lab/manufacturer formed in the early 1990's under financial support from Apple Computer to design PowerPC Compatible Processors that could run at high clock speeds, as Motorola was not very forthcoming. Their primary goal was to get high clock speeds using bipolar logic/BiCMOS designs.
Their only real product was the much praised X704 processor, which was supposed to be used in place of the Motorola 604 and G3 CPUs in the Power Macintosh line. However, Apple pulled their financial support from Exponential Technology before they could bring their chip to market.
As a result, they declared bankruptcy in 1997 and attempted to sue Apple for breach of contract, but were unsuccessful. Their assets were later bought by Motorola, and some of their technologies were used in the G3 and G4 processors.