Today, you can carry around a lot of processing power without much trouble. Netbooks can fit in a purse. Smart phones fit in your pocket. But portable computing has had a long row to hoe. Think about carrying around the IBM 5100 Portable Computer. It was released in 1975. It had a 16-bit processor and 64KB of RAM. And it cost $19,975. Did I mention that it weighed 50 pounds?