The Intel 486 ("eighty-four-eighty-six"), also known as the i486 or 80486 was a higher performance follow-up to the Intel 80386 microprocessor. The 486 was introduced in 1989 and was the first tightly[1] pipelined x86 design as well as the first x86 chip to use more than a million transistors, due to a large on-chip cache and an integrated floating-point unit. It represents a fourth generation of binary compatible CPUs since the original 8086 of 1978.
A 50 MHz 486 executes around 40 million instructions per second on average and is able to reach 50 MIPS peak performance.
The i486 does not have the usual 80-prefix because of a court ruling that prohibits trademarking numbers (such as 80486). Later, with the introduction of the Pentium brand, Intel began branding its chips with words rather than numbers.