DDR4 SDRAM computer buses have migrated towards replacing parallel buses with serial buses, for example by the evolution of Serial ATA replacing Parallel ATA, PCI Express replacing PCI, and serial ports replacing parallel ports. In general, serial buses are easier to scale up and have fewer wires/traces, making circuit boards using them easier to design. In the longer term, experts speculate that non-volatile RAM types like PCM (phase-change memory), RRAM (resistive random-access memory), or MRAM (magnetoresistive random-access memory) could replace DDR4 SDRAM and its successors. GDDR5 SGRAM is a graphics type of DDR3 synchronous graphics RAM, which was introduced before DDR4, and
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