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
Eagle Computer of the clamshell was the reset button, two RS-232 serial ports labeled "Serial A" and "Serial B", a Centronics parallel port labeled "Parallel A", a SASI port labeled "Parallel B", the brightness knob for the monitor, and the on/off switch. The keyboard was well-designed. The keys were black with white lettering. Besides a full typewriter keyboard, there was a complete ten-key number pad on the right, uncommon at that time. Labels on the "front" of the number keys of the typewriter keyboard, and all the keys of the number pad, denoted what function those keys performed in the command mode