The 8086 is first x86 processor; Intel had already proposed 4004, the 8008, 8080 and 8085. This 16-bit processor could handle 1 MB of memory address bus of 20 bits and frequency selected by IBM 4.77 MHz was quite low: processor is 10 MHz at leaving.

Also note that initial PC using derivative of this processor, 8088, which had only data bus 8 bits. For record, control systems of U.S. space shuttles need 8086 and NASA has had to buy eBay in 2002, as Intel could not give.