A magnetic tape recorder uses electromagnets to record audio, video or computer data onto a special plastic ribbon. There are many types of magnetic tape recorders whose design and purpose vary, but they all share a common principle of operation. Information to be recorded is processed by a recording amplifier before being sent to one or more recording heads, which are very precise electromagnets that magnetize a recording tape as it passes over them. The recorded signal can be played back using a different set of heads and a playback amplifier, although inexpensive home tape recorders often use the same set of heads for recording and playback. Magnetic tape recorders in all their forms had been all but replaced by digital recording devices and media by the early 21st century.
The key component of a magnetic tape recorder is the tape itself. The invention of dimensionally stable plastics made recording tape possible. The tape is simply a plastic ribbon that has a magnetic iron-oxide or chromium oxide coating on one side. The width of the recording tape varies, depending on the type of recording to be done.
Audio tape recorders have appeared in many forms over the years, from small, inexpensive reel-to-reel units to large, multi-track recorders used in music studios. Reel-to-reel and cassette tape recorders became the standard home audio equipment and remained so until affordable digital recorders replaced them. Early home computers used standard cassette tape recorders to store computer programs, and early telephone answering machines recorded phone messages on microcassette tapes.
Video tape recorders also have been produced in many forms since they were first invented. The first video tape recorders were large, heavy pieces of equipment that recorded a black-and-white image on tape that was 2 inches (5.08 cm) wide. They were used in early television studios. Color video recorders followed, even before most consumers could afford a color television set.
As electronics technology improved and the science of video recording matured, home video recording systems became available. For years, the Video Home System (VHS) and Betamax formats of video tapes were standard for home recording and commercial movie distribution. In the late 20th century, handheld magnetic video tape recorders became very affordable, replacing the previously used 8-millimeter film cameras.
Another form of magnetic tape recorder was used on industrial and military computer systems. These recorders used magnetic tape to record computer programs and data. The tape used by this type of magnetic tape recorder was 1-2 inches (2.54-5.08 cm) wide.