In the 1970s, very few companies made and sold personal computers. Nobody knew if consumers would want to buy them. But when computers turned out to be popular with consumers, more companies started making and selling them.
What happened to the overall supply of personal computers?
The supply went down. The supply went up.
Overall supply is the total amount of a good or service that producers make and sell. There are several things that can make overall supply go up or down. The table below shows how changes to these things might affect overall supply.
 | Resources | Number of producers or suppliers | Expected change in demand
Supply goes up | when resources cost less or are easier to get | when there are more producers or suppliers | when demand is expected to go up
Supply goes down | when resources cost more or are harder to get | when there are fewer producers or suppliers | when demand is expected to go down
Producers are people or companies that make goods or provide services. Suppliers are people or companies that sell goods or services. New inventions or technologies can also help workers produce goods and services more quickly. As a result of these changes, the supply of a good or service will often go up.
Some of the first computer companies became successful quickly. Other companies saw that a lot of people wanted to buy personal computers. So more companies started selling them. The number of producers went up. So, the supply of personal computers went up.