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Early computers

Operators of early digital computers accessed the computer through paper punch cards, paper tape readout, blinking lights, and teletype machines adapted for computer use. By the mid-1960s, CRT (known as cathode ray tube) displays were used as displays in place of paper, allowing for better flexibility. CRT displays were the technology of television sets at the time. By the mid-1970s, dumb terminals using CRT screens and typewriter keyboards were the standards in interacting with a computer.

In 1943, Thomas Watson, the president of IBM, famously predicted that there was a world market for a possible five computers. In hindsight, this prediction was incredibly wrong. Watson could not have possibly envisioned the technological advancements in computing since the time of his prediction. It is estimated that there are over 2 billion personal computers in use today.

The following diagram shows a mid-1970s computer (called a mainframe) and a dumb terminal. A system such as this would be used by operators for applications such as booking hotel rooms and checking inventory levels:

In this arrangement, the dumb terminal was used only for displaying and entering data. The processing was done by the mainframe computer. Access to the mainframe was controlled by system administrators. The dumb terminal and mainframe would dominate the 1970s; however, a growing interest in bringing computing power to hobbyists and would-be programmers was starting to brew. This period of time would prove to be the dawning of the personal computer era.