Editing Atari 800XL

{{Infobox computer
| name         = Atari 800XL
| image        = [[File:Atari-800XL.jpg|250px]]
| caption      = Atari 800XL home computer
| manufacturer = Atari, Inc.
| type         = Home Computer
| release date = 1983
| discontinued = 1985
| price        = US$299 (1983)
| cpu          = MOS Technology 6502C @ 1.79 MHz (NTSC) / 1.77 MHz (PAL)
| memory       = 64 KB RAM, 16 KB ROM
| storage      = External cassette tape, optional 5.25" floppy disk drive (Atari 1050)
| display      = 320×192 pixels (max), 40×24 text, 16 colours (ANTIC/GTIA)
| sound        = POKEY: 4 voices, 8-bit mono
| dimensions   = 40.6 cm × 24.1 cm × 7.6 cm
| weight       = 2.1 kg
| os           = Atari BASIC (in ROM), Atari OS-B
| predecessor  = [[Atari 800]]
| successor    = [[Atari 65XE]]
| codename     = Sweet-16
| model        = 800XL
}}

The '''Atari 800XL''' is a home computer released by Atari, Inc. in 1983 as part of the Atari 8-bit family. It combined the improved electronics of the XL line with a revised, compact case and a full 64 KB of RAM, becoming one of the most popular Atari 8-bit models worldwide.

== Architecture and Processor ==
The 800XL is powered by the '''MOS Technology 6502C''' microprocessor, running at:
* '''1.79 MHz''' (NTSC systems)
* '''1.77 MHz''' (PAL systems)

The CPU is supported by custom Atari chips:
* '''ANTIC''' – programmable video interface, generating display lists and handling graphics modes.
* '''GTIA''' – manages colour, player/missile graphics, and collision detection.
* '''POKEY''' – provides sound, keyboard scanning, serial I/O, and random number generation.
* '''PIA''' – handles parallel I/O for peripheral connections.

This architecture enabled advanced graphics and sound for its era, with hardware support for smooth scrolling, sprites (player/missile graphics), and multiple display modes.

== Memory and Storage ==
The Atari 800XL features:
* '''64 KB RAM''' – the maximum addressable by the 6502, allowing for more complex software and full compatibility with most Atari 8-bit programs.
* '''16 KB ROM''' – containing the OS-B operating system and Atari BASIC (in most regions).

Storage options include:
* '''Atari 1010 Program Recorder''' – cassette tape drive for data storage and loading.
* '''Atari 1050 Floppy Disk Drive''' – external 5.25" disk drive for faster, more reliable storage.
* '''Cartridge slot''' – for instant-loading software and utilities.

== Display and Graphics ==
Graphics are handled by the ANTIC and GTIA chips, offering:
* '''Resolution:''' up to 320×192 pixels (bitmap mode)
* '''Text:''' 40 columns × 24 rows (default), with hardware support for 20, 40, or 80 columns (via software)
* '''Colours:''' up to 16 on screen simultaneously, with a palette of 256 hues and 16 luminance levels
* '''Player/Missile Graphics:''' 4 players (sprites) and 4 missiles, with collision detection and priority control
* '''Smooth scrolling''' and fine control over display lists, enabling split-screen and mixed-mode graphics

These capabilities made the 800XL a favourite for games and graphics-intensive applications.

== Sound Capabilities ==
Audio is generated by the '''POKEY''' chip, providing:
* '''4 independent voices''' (channels), each with 8-bit resolution
* Programmable frequency, volume, and distortion
* White noise generation for percussion and effects
* Keyboard scanning, serial I/O, and random number generation

The POKEY chip's flexibility allowed for a wide range of sound effects and music, contributing to the system's strong gaming library.

== Input/Output and Expansion ==
The 800XL offers a comprehensive set of I/O ports:
* '''Cartridge slot''' – for game and utility cartridges
* '''SIO (Serial Input/Output) port''' – daisy-chained connection for disk drives, printers, modems, and other peripherals
* '''Parallel Bus Interface (PBI)''' – a 50-pin edge connector for direct memory-mapped expansion (unique to XL models)
* '''2 joystick ports''' – compatible with Atari-standard controllers
* '''Composite and RF video outputs''' – for connection to TVs and monitors
* '''Audio output''' – mono sound via TV or monitor
* '''Power input''' – external power supply

The PBI allowed for advanced expansions, such as memory upgrades and hard disk interfaces, although few peripherals were released for it.

== PCB Schematics & Service Manual ==
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{| class="wikitable styled-table" style="width:75%; text-align:center;"
|+'''Atari 800XL Main Boards'''
|-
! Logic Board !! Schematic Diagrams
|-
| [[File:Atari 800XL board top perspective fix (72RHA AT8489594 I-474) - retouched.jpg|center|thumb|350x350px|Atari 800XL Logic Board]]
| [[File:Atari 800XL Schematics.pdf|center|thumb|800XL Logic Board Schematic]]
|}

* The full Atari 800XL Field Service Manual, including schematics and troubleshooting flowcharts, is available at: [[Atari 800XL Service Manual|Atari 800XL Field Service Manual]]

== Gallery ==
<gallery mode="packed" heights="200">
File:Atari-800XL.jpg|Atari 800XL front view
File:Atari-800XL-Back.jpg|Rear panel with ports
File:Atari 800XL board top perspective fix (72RHA AT8489594 I-474) - retouched.jpg|800XL motherboard
File:Atari 1050 disk drive.jpg|Atari 1050 disk drive
File:Atari 1010 tape drive A.jpg|Atari 1010 Program Recorder
</gallery>

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

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