ABSTRACT
The changes in computers since their inception have been staggering. Just a few decades ago, they were rare, curious, astronomically expensive machines that were so massive that they literally filled large rooms. Mainframe computers of the mid-1970s cost millions of dollars and served hundreds of users but were equipped with just a few hundred kilobytes of memory; today, memory costs just a few dollars per megabyte and personal computers designed for individual users have dozens of megabytes. Similarly, in the early 1980s, a 500 megabyte disk drive cost approximately $25, 000; in contrast, multigigabyte disks now cost just a few hundred dollars.
