Most people agree that computers are the most important (1)______of the 20th century. The first business computers (2)______introduced just about fifty years ago, and now they are being used in a wide variety of fields, from banking to space travel. However, until just a few years ago, computers were very large, expensive machines (3)______by large corporations and governments. Although everyone knew that computers existed, very few people had ever seen one and even fewer had used one. Then in the 1970s the silicon chip was invented. Because this electronic device could (4)______a large amount of information in a very small space, computers could be much smaller and less expensive than the huge mainframe computers used by corporations. Some computer manufacturers believed that people might lie to have computers in (5)______homes, offices, and schools, so the personal computers was born.