1.2) What is the Atari 400?

Introduced in January 1979 alongside the Atari 800 and shipped that fall, the
Atari 400 was the reduced feature set version of the new Atari personal
computer system. 

The 400 is the only 8-bit Atari with a membrane keyboard rather than a full-
stroke keyboard, and is one of the few 8-bit Atari computers lacking a
composite monitor port.  Controller Jacks #1-3 on the 400 are the only ones on
any 8-bit Atari that do not support a light pen / light gun.  The 400 was
originally released with just 8KiB RAM, but most were sold with 16KiB RAM.  As
of June 1983 Atari released the 48K RAM Expansion Kit for the 400, installed
through Atari service centers or offered as a kit through the Atari Program
Exchange (APX).

Any internal plug-in RAM board for the 400 can also be used in the front RAM
slot of the 800.

Features unique to the 400/800 models relative to other Atari computers:
- Television (TV) connecting cable, not designed to be removable, emerges
   directly from center of rear of computer case
- Four controller (joystick) ports
- Internal speaker for keyclicks and system buzzer
- Memo Pad / Blackboard mode
- +12 volt supply on pin 12 of the SIO port
- Internal plug-in 400/800 CPU Board (28/56 pin edge connector)

System initialization types supported:
- Memo Pad: Turn on computer with no cartridge inserted and no powered disk
   drive #1.
- Cartridge: Turn on computer with cartridge inserted.
- Cassette boot: (boot cassette may or may not require cartridge inserted)
    1. Hold down [START] while turning on the computer. (system buzzer sounds)
    2. Press [PLAY] on the program recorder with boot cassette inserted.
    3. Press [RETURN] on the computer.
- Disk boot: (boot disk may or may not require cartridge inserted)
    Turn on computer with boot disk inserted in powered disk drive #1.

Versions of the Atari 400:
  o  Domestic version for NTSC M television (North America)
     - 1979-1981 systems shipped with:
        - 8KiB of RAM
        - Atari BASIC Programming Language cartridge CXL4002
        - Atari BASIC (Wiley Self-Teaching Guide) book C014385
        - Atari 400 Operator's Manual C014768 (CO14768)
     - 1981-1983 systems shipped with:
        - 16KiB of RAM
        - The Basic Computer Owner's Guide C017711
     - Most units: 6502 MPU (MOS Technology MCS6502A or equivalent), C014377
       Late units: 6502 MPU (Atari SALLY), C014806
     - ANTIC NTSC version, C012296
     - Early units: CTIA, C012295
       Most units: GTIA NTSC version, C014805
     - 10KiB Operating System ROM
        - 400/800 OS, C012399 Floating Point Package (FPP) + C012499 + C014599
        - Early units: 400/800 OS Rev.A/NTSC
        - Most units: 400/800 OS Rev.B/NTSC
     - No Monitor port
     - Built-in TV connecting cable for TV antenna input
     - Switch (unlabeled) on back of computer selects TV output RF channel:
       2 or 3
     - TV Switch Box supplied with computer
  o  PAL versions for PAL B/G television (Europe) or PAL I television (UK)
     - Shipped 1981-1983
     - 16KiB RAM
     - 6502 MPU (Atari SALLY), C014806
     - ANTIC PAL 'A' version, C014887
     - GTIA PAL version, C014889
     - 10KiB Operating System ROM
        - 400/800 OS Rev.A/PAL, C012399 (FPP) + C015199 + C015299
     - No Monitor port
     - Built-in TV connecting cable for TV antenna input
     - Switch (unlabeled) on back of computer selects TV output RF channel:
        - Some units: 36 (PAL/UK) or 4 (PAL)
        - Some units (Germany): 3 or 4
        - Some units: Channel is fixed to either 36 or 4
     - "Peritel" PAL version for France has a second built-in TV connecting
       cable for Peritel TV input.  (limited-palette RGB video)
        - http://www.atariage.com/forums/index.php?showtopic=62346&st=25
        - http://preview.tinyurl.com/ngsxhd8
        - Rare!  See L'Atarien #7 p33 for further reference
     - The Atari 400 Computer Owner's Guide C060200 (CO60200)

Additional Manuals:
- Atari 400/800 Personal Computer System Service Manual
    - August 1980
    - May 1981
- Atari 400/800 Home Computer Field Service Manual FD100001
    - June 1982
    - Rev. 02 May 1983
- Atari 400/800 PAL-UK field service manual FD100002

Power: Used with an external 9 volt AC transformer power supply rated for at
least 19 watts: Atari CA014748 or equivalent.

Atari marketing used the trademark, The Basic Computer, as an alternative name
for the 400 from 1981-1982.

The 400 was manufactured at Atari's plant at 1173 Borregas, Sunnyvale CA from
November 1979 to May 1983, and was also made by Atari-Wong Co. in Hong Kong
from January to May 1983.  Serial numbers:
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