Complex sentence: In 1990 IBM wanted a unified instruction set for both 64-bit and 32-bit microprocessors, and therefore decided to use the planned POWER1 processor as a model for the PowerPC.
Split into simpler sentences: In 1990 IBM wanted a unified instruction set for both 64-bit microprocessors and 32-bit microprocessors. IBM decided to use the planned POWER1 processor as a model for the PowerPc.