Atari 400: Difference between revisions
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The '''Atari 400''' is an 8-bit home computer introduced by Atari, Inc. in November 1979. Designed as a more affordable and child-friendly sibling to the [[Atari 800]], the 400 featured a membrane keyboard and robust plastic case, targeting the home computing and educational markets. | The '''Atari 400''' is an 8-bit home computer introduced by Atari, Inc. in November 1979. Designed as a more affordable and child-friendly sibling to the [[Atari 800]], the 400 featured a membrane keyboard and robust plastic case, targeting the home computing and educational markets. | ||
== | == Architecture and Processor == | ||
At the heart of the Atari 400 is the '''MOS Technology 6502''' microprocessor, running at: | At the heart of the Atari 400 is the '''MOS Technology 6502''' microprocessor, running at: | ||
* '''1.79 MHz''' (NTSC systems) | * '''1.79 MHz''' (NTSC systems) | ||
| Line 37: | Line 37: | ||
This multi-chip design allowed the Atari 400 to deliver advanced graphics and sound capabilities for its time. | This multi-chip design allowed the Atari 400 to deliver advanced graphics and sound capabilities for its time. | ||
== | == Memory and Storage == | ||
The Atari 400 was originally shipped with '''8 KB RAM''' (expandable to 16 KB and later 48 KB via third-party upgrades). ROM contained the system OS and I/O routines. Application software and the Atari BASIC interpreter were supplied on plug-in cartridges. | The Atari 400 was originally shipped with '''8 KB RAM''' (expandable to 16 KB and later 48 KB via third-party upgrades). ROM contained the system OS and I/O routines. Application software and the Atari BASIC interpreter were supplied on plug-in cartridges. | ||
| Line 44: | Line 44: | ||
* '''810 floppy disk drive''' – optional 5.25" single-sided, single-density drive (via SIO port). | * '''810 floppy disk drive''' – optional 5.25" single-sided, single-density drive (via SIO port). | ||
== | == Display and Graphics == | ||
Graphics capabilities were a major strength of the Atari 400, provided by the ANTIC and CTIA/GTIA chips: | Graphics capabilities were a major strength of the Atari 400, provided by the ANTIC and CTIA/GTIA chips: | ||
* '''Text modes''': 40×24 and 20×24 characters | * '''Text modes''': 40×24 and 20×24 characters | ||
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The system could output video via RF modulator (for TVs) or composite video (with modification). | The system could output video via RF modulator (for TVs) or composite video (with modification). | ||
== | == Sound Capabilities == | ||
Sound was generated by the '''POKEY''' chip, offering: | Sound was generated by the '''POKEY''' chip, offering: | ||
* '''4 independent audio channels''' | * '''4 independent audio channels''' | ||
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The POKEY chip enabled complex sound effects and music, making the Atari 400 popular for gaming. | The POKEY chip enabled complex sound effects and music, making the Atari 400 popular for gaming. | ||
== | == Input/Output and Expansion == | ||
The Atari 400 included the following I/O and expansion features: | The Atari 400 included the following I/O and expansion features: | ||
* '''Cartridge slot''' – for games and software (Atari BASIC, educational titles, etc.) | * '''Cartridge slot''' – for games and software (Atari BASIC, educational titles, etc.) | ||
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Unlike the Atari 800, the 400 did not include user-accessible internal expansion slots and was limited to its factory RAM configuration (though third-party upgrades became available). | Unlike the Atari 800, the 400 did not include user-accessible internal expansion slots and was limited to its factory RAM configuration (though third-party upgrades became available). | ||
== | == PCB Schematics & Service Manual == | ||
<templatestyles src="Template:StyledTable/styles.css" /> | <templatestyles src="Template:StyledTable/styles.css" /> | ||
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|- | |- | ||
| [[File:Atari 400 mainboard and daughterboard.png|center|thumb|300x300px|Atari 400 Logic Board]]<br> | | [[File:Atari 400 mainboard and daughterboard.png|center|thumb|300x300px|Atari 400 Logic Board]]<br> | ||
| [[File: | | [[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 Service Manual]] | 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="180"> | <gallery mode="packed" heights="180"> | ||
File:Atari-400-Comp.jpg|Atari 400 front view | File:Atari-400-Comp.jpg|Atari 400 front view | ||
| Line 94: | Line 94: | ||
</gallery> | </gallery> | ||
== | == Related Pages == | ||
* [[Atari 400 General Maintenance]] | * [[Atari 400 General Maintenance]] | ||
* [[Atari 400 Troubleshooting Guide]] | * [[Atari 400 Troubleshooting Guide]] | ||
Latest revision as of 17:43, 9 August 2025
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| Atari 400 home computer (1979) | |
| Specifications | |
|---|---|
| Manufacturer | Atari, Inc. |
| Type | Home computer |
| Released | November 1979 |
| Discontinued | 1983 |
| Intro price | US$550 (1979) |
| CPU | MOS Technology 6502 @ 1.79 MHz (NTSC) / 1.77 MHz (PAL) |
| Memory | 8 KB RAM (original), later models 16 KB or 48 KB RAM |
| Storage | External cassette tape (410 Program Recorder), optional 810 5.25" floppy disk drive |
| Display | 40×24 text, 320×192 pixels (max), 128 colours (NTSC: 256 hues x 128 luminances) |
| Sound | POKEY: 4 channels, 8-bit, noise, random, keyboard scan |
| Dimensions | 41 cm × 24 cm × 9 cm |
| Weight | 3.2 kg |
| OS / Firmware | Atari BASIC (cartridge), Atari OS in ROM |
| Successor | Atari 800 |
| Codename | Candy |
| Model no. | CX2624 |
The Atari 400 is an 8-bit home computer introduced by Atari, Inc. in November 1979. Designed as a more affordable and child-friendly sibling to the Atari 800, the 400 featured a membrane keyboard and robust plastic case, targeting the home computing and educational markets.
Architecture and Processor
[edit | edit source]At the heart of the Atari 400 is the MOS Technology 6502 microprocessor, running at:
- 1.79 MHz (NTSC systems)
- 1.77 MHz (PAL systems)
The system architecture is built around custom Atari co-processors:
- ANTIC – programmable video interface controller, responsible for display list processing and graphics generation.
- CTIA/GTIA – handles colour, player/missile graphics (sprites), and video output.
- POKEY – manages sound generation, keyboard scanning, serial I/O, and random number generation.
This multi-chip design allowed the Atari 400 to deliver advanced graphics and sound capabilities for its time.
Memory and Storage
[edit | edit source]The Atari 400 was originally shipped with 8 KB RAM (expandable to 16 KB and later 48 KB via third-party upgrades). ROM contained the system OS and I/O routines. Application software and the Atari BASIC interpreter were supplied on plug-in cartridges.
Storage options included:
- 410 Program Recorder – external cassette tape drive for program and data storage.
- 810 floppy disk drive – optional 5.25" single-sided, single-density drive (via SIO port).
Display and Graphics
[edit | edit source]Graphics capabilities were a major strength of the Atari 400, provided by the ANTIC and CTIA/GTIA chips:
- Text modes: 40×24 and 20×24 characters
- Graphics modes: up to 320×192 pixels (bitmap), with multiple colour and resolution options
- Colours: Up to 128 (NTSC) or 104 (PAL) simultaneous colours via palette and luminance controls
- Sprites: 4 player and 4 missile hardware sprites ("player/missile graphics")
- Smooth scrolling and fine control over display via programmable display lists
The system could output video via RF modulator (for TVs) or composite video (with modification).
Sound Capabilities
[edit | edit source]Sound was generated by the POKEY chip, offering:
- 4 independent audio channels
- 8-bit resolution, with selectable frequencies and noise generation
- Programmable audio control for effects and music
- Integrated keyboard scanning and random number generator
The POKEY chip enabled complex sound effects and music, making the Atari 400 popular for gaming.
Input/Output and Expansion
[edit | edit source]The Atari 400 included the following I/O and expansion features:
- Cartridge slot – for games and software (Atari BASIC, educational titles, etc.)
- 4 joystick ports – supporting Atari-compatible digital controllers
- SIO (Serial Input/Output) port – daisy-chainable connection for cassette, disk drives, printers, modems, and other peripherals
- RF output – for connection to standard television sets
Unlike the Atari 800, the 400 did not include user-accessible internal expansion slots and was limited to its factory RAM configuration (though third-party upgrades became available).
PCB Schematics & Service Manual
[edit | edit source]| Logic Board | Logic Board Schematic |
|---|---|
 |
File:Atari 400 800 Home Computer Schematics.pdf |
Official service manuals and schematics are available via the Atari 400 / 800 Field Service Manual
Gallery
[edit | edit source]-
Atari 400 front view -
Atari 400 Interfaces -
Atari 400 logic board (main PCB) -
Cartridge slot open
