Disk drives have evolved from behemoth stacks of Platters that filled entire rooms and only hold about as much information as a hard drive that can fit in the palm of you hand. The size of these devises is noticeable but the price difference may be the most dramatic difference. You can get 100 gigabytes of disk space for a few hundred dollars where in the early 1970's that same space might have cost you hundreds of thousands of dollars.