Serial port ports with pinouts and voltage levels incompatible with RS-232. Inter-operation with RS-232 devices may be impossible as the serial port cannot withstand the voltage levels produced and may have other differences that "lock in" the user to products of a particular manufacturer. Low-cost processors now allow higher-speed, but more complex, serial communication standards such as USB and FireWire to replace RS-232. These make it possible to connect devices that would not have operated feasibly over slower serial connections, such as mass storage, sound, and video devices. Many personal computer motherboards still have at least one serial port, even if accessible
Serial port a 9-pin D-subminiature connector is not sufficient to indicate the connection is in fact a serial port, since this connector is also used for video, joysticks, and other purposes. Some miniaturized electronics, particularly graphing calculators and hand-held amateur and two-way radio equipment, have serial ports using a phone connector, usually the smaller 2.5 or 3.5 mm connectors and use the most basic 3-wire interface. Many models of Macintosh favor the related RS-422 standard, mostly using German mini-DIN connectors, except in the earliest models. The Macintosh included a standard set of two ports for connection to a printer and a modem,