Then: One of the earliest computers was ENIAC (Electronic Numerical Integrator and Computer), the first true all-purpose electronic computer. Unveiled in 1946, it was a monstrous 30-ton machine with 6000 switches, 18,000 tubes and cabinets, and occupied an entire room.
Now: Take your pick — super slim laptops, ultra light Netbooks, iPads and soon-to-come Android tablets.