The first four generations were defined by hardware: (1) vacuum tubes, (2) transisitors, (3) integrated circuit boards, (4) microprocessor full CPUs on a chip.

The first four generations were defined by hardware: (1) vacuum tubes, (2) transisitors, (3) integrated circuit boards, (4) microprocessor full CPUs on a chip. I would define (5) clusters and (6) mobile. Candidates for next generates include huge data engine clouds, wearables and internet of things.