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
Parallel universes in fiction or unintentionally – as in "Angel Heart". Less often, the alternative narratives are given equal weight in the story, making them truly alternative universes, such as in the German film "Run Lola Run", the short-lived British West End musical "Our House" and the British film "Sliding Doors". More recent films that have explicitly explored parallel universes are: the 2000 film "The Family Man", the 2001 cult movie "Donnie Darko", which deals with what it terms a "tangent universe" that erupts from our own universe; "Super Mario Bros." (1993) has the eponymous heroes cross over into a parallel universe ruled by