The Saturn had technically impressive hardware at the time of its release, but its complexity made harnessing this power difficult for developers accustomed to conventional programming. The greatest disadvantage was that both CPUs shared the same bus and were unable to access system memory at the same time. Making full use of the 4 KB of cache memory in each CPU was critical to maintaining performance. For example, "Virtua Fighter" used one CPU for each character, while "Nights" used one CPU for 3D environments and the other for 2D objects. The Visual Display Processor 2 (VDP2), which can generate and manipulate backgrounds, has also been cited as one of the system's most important features.