sentences:  Despite massive efforts, CPU designs using classic RISC or CISC ISA's have plateaued at about three or four functional units .Additional performance can be wrung from systems by examining the instructions to find ones that operate on different "types" of data and adding units dedicated to that sort of data; this has led to the introduction of floating point units and, more recently, single instruction, multiple data (SIMD) units.The drawback to this approach is that it makes the CPU less generic; feeding the CPU with a program that uses almost all floating point instructions, for instance, will bog the FPUs while the other units sit idle.