Editing Atari 800

{{Infobox computer
| name         = Atari 800
| image        = [[File:Atari800.jpg|250px]]
| caption      = Atari 800 Home Computer (1979)
| manufacturer = Atari, Inc.
| type         = Home Computer
| release date = November 1979
| discontinued = 1983
| price        = US$995 (1979)
| cpu          = MOS Technology 6502 @ 1.79 MHz (NTSC) / 1.77 MHz (PAL)
| memory       = 8 KB – 48 KB RAM (user expandable), 10 KB ROM
| storage      = External cassette tape (410/1010), optional 5.25" floppy disk drive (810/1050)
| display      = 40×24 text, up to 320×192 pixels, 128 colours (NTSC: 16 hues × 8 luminance)
| sound        = 4 voices, 3.5 octaves (POKEY chip)
| dimensions   = 48.3 cm × 34.3 cm × 10.2 cm
| weight       = 5.4 kg
| os           = Atari OS (in ROM), Atari BASIC (cartridge)
| predecessor  = 
| successor    = [[Atari 800XL]]
| codename     = Colleen
| model        = 800
| logo         = [[File:Atari 800 logo-03.svg|250px]]
}}

The '''Atari 800''' is an 8-bit home computer introduced by Atari, Inc. in late 1979, designed as a robust, expandable system for the home and education markets. It was part of the original Atari 8-bit family, featuring advanced graphics and sound capabilities for its era.

== Architecture and Processor ==
The Atari 800 is built around the '''MOS Technology 6502''' microprocessor, running at:
* '''1.79 MHz''' (NTSC systems)
* '''1.77 MHz''' (PAL systems)

The system architecture is highly modular, utilising custom coprocessors:
* '''ANTIC''' (Alphanumeric Television Interface Controller) – handles display list processing and graphics DMA.
* '''CTIA/GTIA''' (Color Television Interface Adapter / Graphic Television Interface Adapter) – manages colour, sprites (player/missile graphics), and collision detection.
* '''POKEY''' (Potentiometer and Keyboard Integrated Circuit) – responsible for sound, keyboard scanning, and serial I/O.

This coprocessor-based design enabled the Atari 800 to deliver advanced multimedia features and flexible video modes.

== Memory and Storage ==
The Atari 800 shipped with:
* '''8 KB RAM''' standard (early units), expandable to '''48 KB RAM''' via plug-in memory cards.
* '''10 KB ROM''', containing the operating system and built-in diagnostics.

Storage options included:
* '''Atari 410/1010 Program Recorder''' – external cassette tape drive for data and program storage.
* '''Atari 810/1050 Disk Drive''' – optional 5.25" floppy disk drive for faster, more reliable storage.
* '''Cartridge slot''' – for instant-load software and BASIC interpreter.

== Display and Graphics ==
Graphics capabilities were a major strength of the Atari 800, driven by the ANTIC and CTIA/GTIA chips:
* '''Text modes:''' up to 40 columns × 24 rows.
* '''Graphics modes:''' resolutions from 40×24 up to 320×192 pixels.
* '''Colour:''' up to 128 colours (NTSC: 16 hues × 8 luminance levels).
* '''Sprites:''' 4 "player" and 4 "missile" hardware sprites (player/missile graphics) with collision detection.
* Smooth scrolling, programmable display lists, and fine control over video memory.

These features allowed for arcade-quality visuals and animation, setting the Atari 800 apart from most contemporaries.

== Sound Capabilities ==
Audio is provided by the '''POKEY''' chip, offering:
* '''4 independent audio channels''' (voices).
* Each channel covers '''3.5 octaves'''.
* Programmable frequency, volume, and distortion settings.
* Additional features: random number generation and keyboard scanning.

The POKEY's flexibility enabled a wide range of sound effects and music, making the Atari 800 popular among game developers.

== Input/Output and Expansion ==
The Atari 800 was designed for expandability and robust I/O:
* '''Two cartridge slots''' (one primary, one auxiliary) for software and hardware expansion.
* '''Four joystick ports''' – compatible with Atari-style controllers.
* '''Peripheral Interface Bus (SIO)''' – daisy-chain connection for disk drives, printers, modems, and cassette recorders.
* '''Composite and RF video outputs''' – for connection to TVs and monitors.
* '''Parallel bus expansion slot''' (underneath) for memory and future upgrades.
* '''Full-travel keyboard''' – 57 keys, including function keys and a HELP key.

The system's modular design and shielded, rugged case made it suitable for both home and educational use.

== PCB Schematics & Service Manual ==
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The Atari 800 consists of a main logic board and plug-in memory cards. Its robust, shielded construction was intended to meet stringent FCC requirements for home electronics.

{| class="wikitable styled-table" style="width:75%; text-align:center;"
|+'''Atari 800 Main Boards'''
|-
! Logic Board !! Logic Board Schematic
|-
| [[File:Atari 800 mainboard and daughterboard.jpg|center|thumb|300x300px|Atari 800 Logic Board]]<br>
| [[File:Atari 400 800 Home Computer Schematics.pdf|alt=Atari 400 / 800 Schematics|center|thumb|Atari 400 / 800 Schematics]]<br>
|}

Official service manuals and schematics are available via the [[Atari 400 800 Field Service Manual June 82|Atari 400 / 800 Field Service Manual]]

== Gallery ==
<gallery mode="packed" heights="200">
File:Atari800.jpg|Atari 800 front view
File:Atari-800-Computer-Port-Side.jpg|Side panel with I/O ports
File:Atari 800 mainboard and daughterboard.jpg|Atari 800 main logic board
File:Atari 410.jpg|Atari 410 Program Recorder (cassette)
</gallery>

== Related Pages ==
* [[Atari 800 General Maintenance]]
* [[Atari 800 Troubleshooting Guide]]
* [[Atari 800 Keyboard Repair Guide]]
* [[Atari 800 Capacitor Replacement Guide]]
* [[Atari 8-bit Family]]
[[Category:Atari Systems]]

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