Released in 1983 as a replacement for the 400, the 600XL is the low-end
version of the 800XL.  The 600XL/800XL include most of the features of the
1200XL, minus the 4 Function keys, the 2 LED lights, and the "ATARI" logo
screen.  But both the 600XL and 800XL have the Atari BASIC language built-in.
In addition, these two systems offer the Parallel Bus Interface (PBI),
providing fast parallel access to the heart of the computer.  The 600XL has
16K RAM.

The Atari 1064 Memory Module expands the 600XL from 16K to 64K RAM.

Boot options:
   Atari BASIC (Rev. B)
      - Turn on computer with no cartridge inserted and no powered disk drive.
   Self Test program
      - Hold down [OPTION] while turning on the computer with no cartridge
        installed and no powered disk drive.
   Cartridge
      - Turn on computer with cartridge inserted.
   Cassette 
      1. Hold down [START] while turning on the computer.  
         (System buzzer sounds.)
      2. Press [PLAY] on the program recorder.
      3. Press [RETURN] to load and run cassette program.
   Disk, with Atari BASIC enabled
      - Turn on computer with disk inserted in powered disk drive.
   Disk, with Atari BASIC disabled
      - Hold down [OPTION] while turning on computer with disk inserted in
        powered disk drive.

Box: "Feature For Feature, Your Best Value"

Versions of the Atari 600XL:

  o  NTSC (North America) version, produced fall 1983 to summer 1984 by
     Atari, Inc.
     - No Monitor port
     - TV Channel switch: 2 - 3

  o  PAL (Europe) version, produced fall 1983 to summer 1984 by Atari, Inc.
     - Includes Monitor port, but this lacks the separate luminance and
       chrominance video signals
     - No TV channel switch

Rare variations of the 600XL:
  o  Some late-model 600XLs were sold with 64K RAM.  These may have only
appeared in Canada.  The box had a round gold foil sticker reading:
"64k Memory -- Now with a full 64k of memory built-in."

5 different types of 600XL/800XL keyboards were nicely documented by Beetle
here: http://www.atariage.com/forums/index.php?showtopic=105170

The 600XL was made in Hong Kong and Japan.

Production of the 600XL was discontinued by July 1984.