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The Atari 400 computer

Manufacturer Atari
Model 400
Date Announced 1979
Date Canceled 1982
Number Produced Hundreds of thousands
Country of Origin USA
Price Approximately $500
Current Value $10-$75
Processor Rockwell 6502
Speed 1.79 MHz
RAM Up to 48K (almost always 16K)
Storage Cassette Tape or 5.25" floppy disk.
Expansion 1 cartridge slots, 2 well protected memory slots and a daisy-chainable expansion bus
Bus N/A
Video Up to 320x192x16 color composite video or TV out standard and much higher resolutions and color depths with low-level programming
I/O I/O bus could connect to an optional interface unit with parallel and serial ports
OS Options Atari OS
Notes The Atari 400 was a very advanced machine for its time. Although it was built around the same microprocessor as many of its direct competitors such as the Apple II Plus and the Commodore Pet it added various co-processors to handle graphics and sound generation tasks. The 400 was the little brother to the 800. It had a membrane keyboard (to protect against spills from the children who were its target market) and less expansion capability.
Related Items in Collection 810 disk drive, 1050 disk drive, software and cartridges, Atari 800
Related Items Wanted Additional disk drives (810, 1050, RANA), cartridges and software. 850 interface, Atari brand joysticks.

Introduced in time for Christmas of 1979 the Atari 400 was the little brother of the Atari 800. It differed from the 800 only in form, not in function. Both Atari computers had the same processor and chip sets. The 400 had a membrane keyboard (kid safe) where the 800 had a full-travel keyboard and the 400 was limited to one expansion slot and, at least initially, a fixed 16k of RAM.

The Atari 400 computer is a 6502 based machine with custom graphics and sound chips that made it a gamers delight. The Atari line had a fairly wide variety of peripherals available including tape and disk drives, printers, modems and interface units. The 400, like the 800, was compatible with them all.

The Atari 400 also worked with all Atari computer cartridges that could run in its more limited RAM.

The Atari 400 Computer System - boxed

A new boxed example of the Atari 400 was recently added to my collection.

The Educator and Entertainer boxes for the Atari home computers

It came with boxed Educator and Entertainer packages, also from Atari.

Atari 410 Program Recorder

Included with the Educator package is a nice, clean and apparently never used Atari 410 program recorder.

Elsewhere in the other boxes are near-new examples of several Atari game and application packages and paddles and joysticks still in their boxes.

(Submitted June 24, 2012 11:04:10 by arnold)

just bought an atari 400 from a garage shop i would like to sell it. it needs repair the game is not gettin any electric current

(Submitted May 22, 2012 21:25:43 by Josh Turner)

I need a power adapter for a 400 i found at good will please help

(Submitted April 23, 2012 04:13:34 by Buy atari 400)

1 - atari 400 computer with manual and box 2 - atari 800 computer with manual and box

If you have one of these items to sell please send pics to my email and report the value.

Only original items and without modifications.

Thank you.

(Submitted November 4, 2011 19:56:00 by Ken)

My mother bought me an Atari 800 when I was 15. I am now 45 and proud to say that I still have that 800 and it still works! I have also collected, and rescued from Goodwill and other places, several Atari computers and accessories. Love Atari, but hate Commodore! Enough said!

(Submitted August 22, 2011 21:22:53 by Mark Beeman)

Looking for an Atari 400 in working condition. Prefer upgraded to at least 32K. Would also like the 1050 floppy drive if you have it. E-mail me if you are interested in selling.

(Submitted March 31, 2011 20:09:48 by Joey)

with the correct modifications, there would be no difference between the 400 and 800. there was a 48k ram upgrade and there is a way to put a composite out and s video out on it. there are even the correct control lines in the cartridge port that one could build an adapter to plug a right cartridge from an atari 800 into the port. there were also better keyboards like the atari 800's full keyboard.

(Submitted January 19, 2011 15:10:11 by sheyla )



(Submitted December 18, 2010 13:33:00 by Randy Dietz)

Looking for atari equipment.BEST ELECTRONICS in california HAS IT ALL.i have super pac-man (PROTOTYPE) for atari 400.i like the 400 because the games are like the 5200 but i can use the 2600 joysticks

(Submitted December 8, 2010 19:05:42 by Rickie)

I have a complete Atari 400 system for sale. You can see it on my Craigslist posting in the Dallas, TX area.

(Submitted November 20, 2010 09:19:12 by Kumar)

I had an atari 400 when I was a child and I sometimes think that typing on the iphone/ipad is a throwback to atari 400. The keyboard feel is similar for these devices.

(Submitted August 12, 2010 18:51:03 by Aaron Quandt)

Is your Atari 400 for sale? If so, how much? please give me some specifics. Thanks, Aaron Quandt

(Submitted October 21, 2009 13:25:56 by Susan Vigevani)

I have an Atari 400 but I need a powerpack Do you know where I can get one?

(Submitted September 16, 2009 16:14:40 by Ian)

RE the Atari 400 with the real keyboard; The Real keyboard was an aftermarket upgrade that sold for about $100 new. plus installation of course.

(Submitted August 14, 2009 10:11:23 by Cindy Leifer)

I have an Atari 400 with controllers, mouse, manual, tape program recorder and 7 games: defender, centipede, basic, pac-man, missile command, asteroids, and star raiders. Make me an offer and I'll sell it to you.

(Submitted June 15, 2009 14:09:52 by Chris Conlon)

Hi, I too loved the Atari 400 and have recently rescued my dad's old machine, in original packing and saved it going to the tip. It comes complete with everything and their are loads of games. Also an 800xl with all accessories and games. If anyone is interested in purchasing then please get in touch. These really were fantastic machines in their day!

(Submitted June 9, 2009 21:31:33 by Harlock)

For those who connect their 400 or 800 to a tv, the cable coming out the back is NOT composite video. It's RF signal. you must get the proper connector or switchbox to connect it to the cable / antenna input and use the right tv channel which was usually channel 3 or 4 in north america.

BTW, I'm a long time Atari computer user, I have an 800, pair of 600XL's, 65XE and 130XE and various accessories and software. I also have the Toronto Atari Federation disk library as I was working on the TAF library cd-rom some time ago.

(Submitted November 22, 2008 12:10:41 by Clyde List)

The Atari graphics chip was the best part. It was designed by Jay Minor, an interesting fellow who despised the man who owns Atari Inc. today, Jack Tramiel. Jay had designed chips for the Atari Amiga which he suddenly refused to release to the company, insisting they did not work. In any case, Jay's graphic chip for the Atari 400 enabled tasks no computer can do today. You could see all the non-copyrighted memory in your system. You could divide the video screen into as many as 255 different windows and watch a load/store routine at work. It was like raising the hood on your automobile to watch the engine work. I remember watching a tape cassette load/store memory into my 400 and realizing there wasn't enough room. I needed more memory! Every computer classroom should have an Atari 400 in working condition. For me at least, it was a learning experience like no other computer I ever owned.

(Submitted November 11, 2008 06:01:13 by Lavita Deloatch)

I am currently looking for a repairshop to fix my atari 400.I'm also looking for games and other accessories for it as well.If you can offer any info please e-mail me. Thank YOU!!!

(Submitted July 31, 2008 03:17:24 by Rafael Trioxin)

I have one, in perfect work, IM from Brazil/S„o Paulo/MauŠ

(Submitted June 27, 2008 17:08:33 by Bob H)

I have an Atari 400 for sale. It is still in box and comes with all that came with it for set up. Games also included with track ball, are; Quix, Robotron, Centepede, Ms. Pacman, Pacman, Dig-Dug. Only one Kraft joystick survived. If interested contact me at

(Submitted December 18, 2007 21:50:15 by Carlton)

The 400 was excellent. I spent countless hours programming in BASIC, learning from code in the back of magazines. That machine provided for my future by setting a direction for me. Since mine disappeared, I am trying to find a replacement, but it's been difficult to win ebay auctions for these things. Evidently everyone still wants one. :)

(Submitted November 16, 2007 14:03:00 by Najeh Ben Kacem)

I have a computer and its new and i want to sell it. This computer arent inatlaion and made in 1992 (15) jears old and with all Accessories. are you intersted ?? please mail back . I am from germany. and plesa i want that my name is anyme. thanks

(Submitted September 25, 2007 01:33:51 by mike)

i had an ATARI 400 that i programmed using Basic. Peek and Poke statements

(Submitted December 5, 2006 20:34:11 by Tara )

I am looking to buy a few games for the atari 400/800. Does anyone know where I could find a few? Thanks, Tara

(Submitted October 13, 2006 13:36:25 by Eric)

The Atari 400 and 800 were capable of 320 x 192 in 256 colours using interlacing and Display List Interrupts (DLIs). Plenty of games and demos came out which showed off this ability at the time. No other home computer was capable of this colour resolution at the time - as inflexible as it was.

(Submitted September 9, 2006 20:06:54 by Ray Taylor)

For those trying to hook your old atari up to a modern tv, note that it does not just 'plug in', you will need to tune it to a preset channel also.

(Submitted July 10, 2006 12:31:45 by (a href=mailto:)tom(/a))

The Atari 400 is not worth a whole lot, unless you have alot of software and accessories, so please don't think you've hit a goldmine.

Also, on the connection, the 400 should have a switch box with it. The box has a slider from computer to TV. To use it you have to hook the computer video cable to it and then have a converter to convert the two wires to a coaxial connection. The converter is fairly cheap.

You can't just insert the video plug directly into the A/V or coax jack on your TV.

(Submitted February 27, 2006 14:16:40 by Tony)

For Kari. I've got one of those! I found it at some car boot ('garage') sale years and years ago: it's a 400 which had it's keyboard replaced by a real one. Shame that it didn't work, but still. . . I assume that one could have the membranes replaced by keys - if it happened here in the UK it must have happened in the States.

(Submitted January 21, 2006 06:47:32 by frank)

I found an old atari 400 promotional video tape... it is really funny. I was a dealer for Atari in 1979. I am making it into an mpeg I video file... I will trade to someone for an atari T-shirt.

(Submitted January 2, 2006 21:36:36 by Kari)

has anyone seen an atari that is a mix of the 400 and 800? the atari i have has the keyboard of the 800 but the cartridge spot of a 400 and i cant find one like it anywhere else. just curious if anyone knows anything about it.

(Submitted December 1, 2005 08:34:16 by steeldude)

i got a atari 400 on ebay but it wont work on my tv doe's the vidio card go to the vidio on tv and i put it on vidio on tv and still don't work

(Submitted June 16, 2005 09:10:03 by jerry )

Dude if you want to keep your old pc's in top condition you need a technical service manual personally i have the service manuals for the ATARI CX5200, ATARI 400, ATARI 500, also the 810 Disk drive, 410 TAPE drive. I have multiple copys of some. I found these in the back of an old tv shop the boss said to get rid of em' along with these are service bulletins, tech tips,revision requests, and other goodies. might be generous and post a site but only if responce is desernable.

feel free to e-mail me!

(Submitted May 16, 2005 01:52:01 by Jordan Bouzeneris)

(Damn, I make one small statement about ram & all the hardware hackers start talking)

(Submitted April 15, 2005 16:33:41 by chris)

I am looking for an old atari game that I loved, i thini it was called king of the mountian,none of the atari web pages have it listed as existing, it was a little man that had to run through caves looking for something, it was over 20 years ago and I am having no luck, was hoping some else out there besides my little brother remembers it

(Submitted November 27, 2004 12:04:09 by Shannon Smith)

I just found my Atari 400 while cleaning out my parent's basement. I'm trying to hook it up to my 2004 TV set, figuring I could just insert the video jack into one of my video inputs. Thing is it's not working ... any ideas or solutions?

(Submitted November 1, 2004 14:04:19 by Lane Flinders)

Would any of you be interested in buying the upgradeable 48kb of RAM hardware for the Atari 400? I found the hardware at a thrift shop in its original box and manuals. Let me know if its even worth anything or not. Lane

(Submitted October 24, 2004 12:23:22 by stefan oetter)

I had an Atari 400 that came with 16k. I remeber having to solder in exta memory. My big dilema at the time was 48k or 64k. I went for 48k assuming one would NEVER need 64 in a computer! P.S. I'd also added the Happy Computing disk duplicator and regular keyboard.

(Submitted October 19, 2004 11:33:23 by Tom Gurak)

I have an Atari 400 that a friend and I upgraded with 64K-bit chips, giving the machine a total of 52KB of RAM. At the same time, we replaced the membrane keyboard with a real one. And yes, it definitely was a color machine.

(Submitted September 21, 2004 10:10:11 by Steve Holcroft)

The Atari 400 was very definitely a colour machine. I can't remember the resolution exactly, but I remember programming in colour and playing colour games.

(Submitted July 23, 2004 12:20:03 by Jordan Bouzeneris)

The Atari 400 did have 16kb of fixed ram, but was upgradeable to 48kb. I wouldn't try to find one, they where only upgradable by sending your 400 to a service center and no one did.

(Submitted July 19, 2004 15:30:42 by Dan Ritter)

I think you got the video description completely wrong on the Atari 400 and the other atari 8bits if you used this same description for the video (I haven't looked yet). But the 320x200 resolution was 1 bit color (meaning black and white with no grey levels). However some color (Red and Blue) could be done with something called artifacting. I don't completely understand artifacting but it has something to do with the frequencies generated by the video chip and the effective resolution using this technique would be 160x192. I know of no other abilities even when using machine language low level programming for any of the atari 8bits to do any higher resolutions.

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