Whatever output device you choose, you will have to connect it to the computer. This is called an interface. There are two types: one is serial, the other parallel [Note: USB and a few others have been added].
Their names describe the functions. Recall that there are eight bits to a byte (character) of data. In a serial interface each bit is sent to the printer individually. A parallel interface sends all eight bits at once. Each interface has its quirks. The key is making certain that you have the correct one. They will not intermix.
Computer Communications
Very often two computers need to "talk" with one another. This is often accomplished by attaching a modem to each computer and connecting them via the phone system. The serial port of the computer is used for the modem since data is transmitted a bit at a time.
Modem is short for MOdulator/DEModulator. The device is presently needed because computers are digital devices and telephones are designed to handle analog information. Thus, a translator is necessary at each end of the phone line. At the transmitting end, the modem converts digital to analog and at the receiving end, the other modem converts the analog tones back to digital signals the computer can process. Modems operate at different speeds, using a variety of data compression techniques. In order to communicate properly the modems at each end of the line must use the same communications parameters.
As the telephone system converts from analog to digital, communications between computers will become easier and more routine.
Analog/Digital
Analog can be thought of as being "continuous." In an analog signal there are essentially an infinite number of possible values the signal can take on. In a digital signal, by contrast, there are only a certain number of defined values the signal can have.
Sound, as you hear it, is an analog signal. A sound can be loud, soft, or anywhere between.
Traffic lights are more like digital signals. They can take on only three discrete values: green, yellow, or red. Nothing between.
Networks
Networks are another way for computers to communicate with one another.
Networks are handy for sharing information between workstations, for managing a large database that several computers must have access to, and for sharing resources between several computers (e.g. an expensive printer that everyone can send output to over the network). Electronic mail is another serious application for networks.
Big networks are relatively difficult to set up and maintain. If you plan to establish a network, extensive planning is recommended.
