Solid state/computers: New options from big chips: Large microprocessor dice mean circuit designers must design `smarter¿

The 16-bit 8086 microprocessor introduces to MOS digital design some speed-up techniques well-known to computer architects. Limits on the die size barred these techniques in the past, but with new MOS processes, transistor packing densities are sufficient to use them. As a result, it is possible to design significantly improved performance into the 16-bit 8086 without relying totally on the faster circuits allowed by the new MOS processes. A somewhat novel approach was selected instead for the 8086 design. It was decided to leave out any circuit that did not speed up most of the instructions and to use a system of processor pipelining to increase the average speed of the instruction set. In this way performance is maintained without allowing the die size to grow dangerously large. The 8086 operates under microprogram control. When handled properly, microcode can drive a processor as fast as random logic control.