Complex sentence: Atari withdrew largely from the computer market in 1993, and completely in 1995-1996 when Atari merged with JTS and all support for the platform by Atari was dropped, and the systems Atari had built became increasingly left behind as newer and faster systems came out.
Split into simpler sentences: Atari withdrew largely from the computer market in 1993, and completely in 1995-1996 when Atari merged with JTS and all support for the platform by Atari was dropped. The systems Atari had built became increasingly left behind as newer and faster systems came out.