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
Sega TeraDrive similar in design to 9-pin male serial ports, and 2 PS/2 ports to the right side of the unit to accommodate for the mouse and keyboard. The system also contained several ports to its rear. In order from left to right: 9-pin male serial port, 25-pin parallel port for connection to a printer, stereo RCA jacks and composite NTSC video output for connection to a TV, analogue RGB for monitor connection, and a 2nd 9-pin male serial connector labelled "EXT", similar to that found on the rear of an original Mega Drive base unit. The motherboard also had a spare