 VGA is referred to as an "Array" instead of an "adapter" because it was implemented from the start as a single chipan application-specific integrated circuit (ASIC) which replaced both the Motorola 6845 video address generator and the dozens of discrete logic chips that covered the full-length ISA boards of the MDA and CGA.More directly, it replaced the five custom LSIs (including a custom replacement for the 6845) and many discrete logic chips on the EGA board.Its single-chip implementation allowed the VGA to be placed directly on a PC′s motherboard with a minimum of difficulty, which in turn increased the reliability of the video subsystem by reducing the number of component connections, since the VGA required only video memory, timing crystals and an external RAMDAC.