4004 8080 8008 8086 8088 1971 1978 1979 Introduced 1972 1974 Clock speeds 108 kHz 108 kHz 2 MHz 5 MHz, 8 MHz, 10 MHz 5 MHz, 8 MHz Bus width 4 bits 8 bits 8 bits 16 bits 8 bits 29.000 Number of transistors 2,300 3,500 6,000 29,000 6 6 10 Feature size (Lum) 16 KB 1 MB 1 MB Addressable memory 640 Bytes 64 KB Virtual memory