Editing Atari 8-bit computers (section)

==Software==
{{Main|Atari 8-bit computer software}}

Atari did not initially disclose technical information for its computers, except to software developers who [[non-disclosure agreement|agreed to keep it secret]], possibly to increase its own software sales.{{r|nelson198006}} Cartridge software was so rare at first that ''InfoWorld'' joked in 1980 that Atari owners might have considered turning the slot "into a fancy ashtray". The magazine advised them to "clear out those cobwebs" for Atari's ''[[Star Raiders]]'',<ref>{{cite news|title=Star Raiders from Atari|work=InfoWorld|date=July 7, 1980|author=Cole, David C.|pages=13}}</ref> which became the platform's [[killer app]], akin to [[VisiCalc]] for the Apple II in its ability to persuade customers to buy the computer.<ref>{{cite magazine|url=https://archive.org/stream/byte-magazine-1981-05/1981_05_BYTE_06-05_Software_Piracy#page/n107/mode/2up|title=Star Raiders|magazine=BYTE|date=May 1981|author=Williams, Gregg|pages=106}}</ref>{{sfn|Goldberg|Vendel|2012|p=526}}

[[Chris Crawford (game designer)|Chris Crawford]] and others at Atari published detailed technical information in ''[[De Re Atari]]''.<ref>{{cite news |url=https://archive.org/stream/Atari_Program_Exchange_catalog_Fall_1983#page/n35/mode/2up|title=The quarterly APX contest / APX: Programs by our users...for our users / Publications / Hardware|work=APX Product Catalog|date=Fall 1983 |access-date=July 29, 2014|pages=34, 72}}</ref> In 1982, Atari published both the ''Atari Home Computer System Hardware Manual''<ref>{{cite book|title=Atari Home Computer System Hardware Manual|year=1982|publisher=Atari, Inc.|url=http://www.atarimania.com/documents/atari-400-800-hardware-manual.pdf}}</ref> and an annotated source listing of the operating system. These resources resulted in many books and articles about programming the computer's custom hardware.

Because of graphics superior to those of the Apple II<ref>{{cite news|url=https://archive.org/stream/byte-magazine-1982-07/1982_07_BYTE_07-07_Computers_in_the_Arts_and_Sciences#page/n381/mode/2up|title=Computers for Humanity|work=BYTE|date=July 1982|author=Pournelle, Jerry|pages=392}}</ref> and Atari's home-oriented marketing, games dominated its software library. A 1984 compendium of reviews used 198 pages for games compared to 167 for all others.<ref>{{cite book|url=https://archive.org/stream/Atari_Software_1984#page/n3/mode/2up|title=The Addison-Wesley Book of Atari Software|publisher=Addison-Wesley|year=1984|pages=TOC,12,210|isbn=0-201-16454-X|editor1=Stanton, Jeffrey|editor2=Wells, Robert P.|editor3=Rochowansky, Sandra|editor4=Mellid, Michael}}</ref>

===Built-in operating system===
[[File:Atari Computer Memo Pad.png|thumb|When no other program is available, the Atari 400 and 800 boot into Memo Pad: a fullscreen text editor which can't save or load.]]

The Atari 8-bit computers have an operating system built into the [[read-only memory|ROM]]. The Atari 400 and 800 have two versions:
*OS Rev. A – 10 KB ROM (3 chips) early machines
*OS Rev. B – 10 KB ROM (3 chips) most common

The XL/XE all have OS revisions, which created compatibility issues with certain software. Atari responded with the Translator Disk, a floppy disk which loads the older 400 and 800 Rev. 'B' or Rev. 'A' OS into the XL/XE computers.
*OS Rev. 10 – 16 KB ROM (2 chips) for 1200XL Rev A
*OS Rev. 11 – 16 KB ROM (2 chips) for 1200XL Rev B (bug fixes)
*OS Rev. 1 – 16 KB ROM for 600XL
*OS Rev. 2 – 16 KB ROM for 800XL
*OS Rev. 3 – 16 KB ROM for 800XE/130XE
*OS Rev. 4 – 32 KB ROM (16 KB OS + 8 KB BASIC + 8 KB Missile Command) for XEGS

The XL/XE models that followed the 1200XL also have the [[Atari BASIC]] ROM built-in, which can be disabled at startup by holding down the silver <code>OPTION</code> key. Originally this was revision B, which has some serious bugs. Later models have revision C.

===Disk Operating System===
{{Main|Atari DOS}}

The standard Atari OS only contains low-level routines for accessing [[floppy disk]] drives. An extra layer, a [[disk operating system]], is required to assist in organizing [[file system]]-level disk access. [[Atari DOS]] has to be booted from floppy disk at every power-on or reset. Atari DOS is entirely menu-driven.

*DOS 1.0
*DOS 2.0S – Improved over DOS 1.0; became the standard for the 810 disk drive.
*DOS 3.0 – Came with 1050 drive. Uses a different disk format which is incompatible with DOS 2.0, making it unpopular.
*DOS 2.5 – Replaced DOS 3.0 with later 1050s. Functionally identical to DOS 2.0S, but able to read and write [[Atari DOS#Disk formats|enhanced density]] disks.
*DOS XE – Designed for the [[Atari XF551]] double-density drive.

[[Atari DOS#Third-party DOS programs|Third-party replacement DOSes]] were also available.