Editing Atari 2600 (section)

===Graphics===
{{Main|Television Interface Adaptor}}
{{anchor|Racing the beam}}
[[File:A2600 Pitfall.png|thumb|''[[Pitfall!]]'' (1982) has more advanced graphics than the games the VCS launched with. The black bar on the left provides extra time for the program to prepare graphics between each scanline.<ref name=":0" />]]

The Atari 2600 was designed to be compatible with the [[cathode-ray tube]] television sets produced in the late 1970s and early 1980s, which commonly lack auxiliary video inputs to receive audio and video from another device. Therefore, to connect to a TV, the console generates a [[radio frequency]] signal compatible with the regional television standards ([[NTSC]], [[PAL]], or [[SECAM]]), using a special switch box to act as the television's antenna.<ref>{{cite journal |last1=Arceneaux |first1=Noah |title=Review Article: Game theories, technologies and techniques of play |journal=New Media & Society |date=19 February 2010 |volume=12 |issue=1 |pages=161–166 |doi=10.1177/1461444809350996|s2cid=220595570 }}</ref><ref name="ieee decuir"/>

Atari developed the [[Television Interface Adaptor]] (TIA) chip in the VCS to handle the graphics and conversion to a television signal. It provides a single-color, 20-bit background register that covers the left half of the screen (each bit represents 4 adjacent pixels) and is either repeated or reflected on the right side. There are 5 single-color [[Sprite (computer graphics)|sprites]]: two 8-pixel wide ''players''; two 1 bit ''missiles'', which share the same colors as the players; and a 1-pixel ''ball'', which shares the background color. The 1-bit sprites all can be controlled to stretch to 1, 2, 4, or 8 pixels.<ref name="Wright">{{citation|last=Wright|first=Steve|title=Stella Programmer's Guide|date=1979-12-03}}</ref>

The system was designed without a [[frame buffer]] to avoid the cost of the associated [[Random-access memory|RAM]]. The background and [[Sprite (computer graphics)|sprites]] apply to a single [[scan line]], and as the display is output to the television, the program can change colors, sprite positions, and background settings. The careful timing required to sync the code to the screen on the part of the programmer was labeled "[[racing the beam]]"; the actual game logic runs when the television beam is outside of the visible area of the screen.{{sfn|Montfort|Bogost|2009}}<ref name="Wired racing"/> Early games for the system use the same visuals for pairs of scan lines, giving a lower vertical resolution, to allow more time for the next row of graphics to be prepared. Later games, such as ''Pitfall!'', change the visuals for each scan line or extend the black areas around the screen to extend the game code's processing time.<ref name="gi activision start" /><ref name=":0">{{Cite magazine|url=https://www.wired.com/2009/03/racing-the-beam/|title=Racing the Beam: How Atari 2600's Crazy Hardware Changed Game Design|last=Kohler|first=Chris|date=March 13, 2009|magazine=[[Wired (magazine)|Wired]]|archive-url=https://web.archive.org/web/20140712094639/https://www.wired.com/2009/03/racing-the-beam/|archive-date=July 12, 2014|url-status=live}}</ref>

Regional releases of the Atari 2600 use modified [[Television Interface Adaptor|TIA]] chips for each region's television formats, which require games to be developed and published separately for each region. All modes are 160 pixels wide. [[NTSC]] mode provides 192 visible lines per screen, drawn at 60&nbsp;[[Hertz|Hz]], with 16 colors, each at 8 levels of brightness. [[PAL]] mode provides more vertical scanlines, with 228 visible lines per screen, but drawn at 50&nbsp;Hz and only 13 colors. [[SECAM]] mode, also a 50&nbsp;[[Hertz|Hz]] format, is limited to 8 colors, each with only a single brightness level.<ref name="Wright"/><ref name="TIA color chart">Atari 2600 [http://www.biglist.com/lists/stella/archives/200109/msg00285.html "TIA color chart"] {{webarchive |url=https://web.archive.org/web/20110707234118/http://www.biglist.com/lists/stella/archives/200109/msg00285.html |date=July 7, 2011 }}</ref>