Computers are much, much smaller and many times smarter now. Computers don't really think. They manipulate binary digits, one's and zero's, like the beads of an abacus, only much faster.
Computers can compete at chess because the board's options are limited.
When chess grandmaster Garry Kasparov faced off IBM'S Deep Blue, the machine won. That upset a lot of people. I'm real good at that. Look at my desk. Some people say a cluttered desk is a sign of a creative mind.