IBM did not specify an expanded form of "XT" on the machine, press releases, brochures or documentation, but some publications expanded the term as " eXtended Technology " or just " eXTended ". The XT was regarded as an incremental improvement over the PC and a disappointment compared to the next-generation successor that some had anticipated. The number of expansion slots in the original IBM PC was a limiting factor for the product, since essential components such as the video controller, disk controller and printer interface each came as separate expansion cards and could quickly fill up all five available slots, requiring the user to swap cards in and out as tasks demanded.