Released along with the 400 in 1979, the 800 was the high-end model of the
two.  The 800 is the only 8-bit Atari with a Right Cartridge slot, in addition
to the Left Cartridge slot as present on all 8-bit Ataris.  Originally
released with just 8K RAM, many were sold with 16K, later on 48K was standard.

The 800 is also the only 8-bit Atari with a four-slot modular design, where
the first slot holds the CX801 (NTSC) or CX801.P (PAL) 10K ROM module, and
the other three slots hold combinations of CX852 8K or CX853 16K RAM modules.

Jason Harmon writes: (12 Feb 2004)
"..the early ones had plastic cases on the ROM and RAM modules, and had two
thumb tabs to remove the cover to access the modules.  Later model 800s had
48K standard, and to improve cooling Atari installed them without the cases
but put a small plastic strip across the tops of the cards to hold them in
position.  These machines also lost the thumb tabs and have regular screws to
secure the cover over the memory slots."

Most Atari 800 machines include a standard 6502 microprocessor, but late-
production units use a revised CPU Board that features Atari's SALLY 6502.

Features unique to the 400/800 models:
  - Four controller (joystick) ports
  - Internal speaker for keyclicks and system buzzer
  - Memo Pad mode
  - +12 volts on pin 12 of the SIO port

Boot options:
   Memo Pad
      - Turn on computer with no cartridge inserted 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
      - Turn on computer with disk inserted in powered disk drive.

Versions of the Atari 800:

  o  NTSC (North America) version
     - TV Channel switch: 2 - 3
     - CTIA (early production) or GTIA (most)

  o  PAL (Europe) version
     - TV Channel switch (channels vary by country)
     - GTIA

Rare variation of the 800:
  o  At least some of the few Atari 800 units (PAL) sold by Atari in France
have been reported to include an 8-bit DIN monitor port.  PICTURES, ANYONE???
http://www.atariage.com/forums/index.php?showtopic=62346&st=25

The 800 was made in the USA.

Production of the 800 ended in May 1983.