The Atari 600XL, introduced in 1983 was Atari's low end replacement for the discontinued Atari 400 personal computer. The 600XL came with 16K of memory, built-in BASIC and had a PBI Parallel Bus Interface on the rear of the unit to acomodate Parallel Bus expansion devices such as the Atari 1064 64K memory module and the Atari 1090XL Expansion System. The Atari 600XL, just like the Atari 400 lacked a composite video output port. Conversations with several Atari Home Computer Division engineers revealed that originally the Atari 600XL was going to have composite video, but it was cut from the final design for cost reduction. The Atari 600XL looks slightly smaller then the 800XL but with the exception of the lack of composite video and 16K instead of 64K (standard on the 800XL), the Atari 600XL personal computer was functionally equivalent to the 800XL personal computer.