Input and output equipment allows people and computers to communicate. Input devices convert data and programs that humans can understand into a form the computer can comprehend.
These devices translate the letters, numbers, and other natural-language symbols that humans conventionally use in reading and writing into the configurations of 0 and 1 bits that the computer uses to process data.
Output devices, on the other hand, convert the strings of bits the computer uses back into natural- language form to make them understandable to humans. These devices produce output for screen display, output onto paper or film, and so forth.
The equipment we are about to discuss can be classified in a number of ways. Some of it is peripheral equipment. These are input or output devices that are normally under the computer’s direct control.
Display devices and printers are examples. Other input or output equipment, such as many electronic cash registers and computer output microfilm (COM) devices, are auxiliary equipment. These devices normally work independently of the main CPU.
Some auxiliary devices prepare input data for later mounting onto a peripheral device. Others convert output produced on a peripheral device into a form more useful to humans.
This equipment, of course, can also be discussed in terms of its input or output functions. Teleprinters, for example, are capable of both input and output. Keyboards and optical character recognition devices are designed primarily for input.
Printers, monitors, and most computer microfilm devices, on the other hand, specialize in output. Most input and output devices contain limited storage capacity as well.
Output devices produce results in either hard copy or soft copy form. The term hard copy generally refers to output that has been recorded onto a medium such as paper or microfilm- in other words, output that is in a permanent and highly portable form.
Printed reports and program listings are among the most common examples. The term soft copy, on the other hand, generally refers to display output- output that is temporary and of limited portability.