Burroughs (1961–1986) B5000 1961 initial system, 2nd generation (transistor) computer B5500 1964 3x speed improvement(?)[2] B6500 1969 3rd generation computer (integrated circuits), up to 4 processors B5700 1971 new name for B5500 B6700 1971 new name/bug fix for B6500 B7700 1972 faster processor, cache for stack, up to 8 requestors (IO or Central processors) in one or two partitions.