Editing Space Invaders (section)

===Hardware===
{{multiple image
<!--image 1-->| image1            = Space Invaders.JPG
| caption1          = Cocktail [[table arcade cabinet]]
<!--image 2-->| image2            = Tilt byte - 10.jpeg
| caption2          = A modified Space Invaders [[arcade cabinet]]
}}

Nishikado designed his own custom hardware and development tools for ''Space Invaders''.<ref name="GI-177" /><ref name="Edge-Taito" /> It uses an [[Intel 8080]] [[central processing unit]] (CPU), displays [[raster graphics]] on a [[CRT monitor]] using a [[bitmap]]ped [[framebuffer]], and uses [[monaural sound]] hosted by a combination of [[analog circuitry]] and a [[Texas Instruments SN76477]] [[sound chip]].<ref name="KLOV-SI">{{cite web |url=http://www.klov.com/game_detail.php?game_id=9662 |title=Space Invaders Videogame by Bally Midway (1978) |publisher=[[Killer List of Videogames]] |access-date=May 12, 2008 |archive-date=November 25, 2010 |archive-url=https://web.archive.org/web/20101125042142/http://www.arcade-museum.com/game_detail.php?game_id=9662 |url-status=live }}</ref><ref name="1UP-10things" /><ref>{{cite book |title=The Art of Game Worlds |first=Dave |last=Morris |page=166 |publisher=[[HarperCollins]] |isbn=0-06-072430-7 |year=2004}}</ref> The adoption of a microprocessor was inspired by ''[[Gun Fight]]'' (1975), [[Midway Games|Midway's]] microprocessor adaptation of Nishikado's earlier [[discrete logic]] game ''[[Western Gun]]'', after the designer was impressed by the improved graphics and smoother animation of Midway's version.<ref>{{citation |author=Chris Kohler |year=2005 |title=Power-Up: How Japanese Video Games Gave the World an Extra Life |chapter=Chapter 2: An Early History of Cinematic Elements in Video Games|chapter-url=https://books.google.com/books?id=auMTAQAAIAAJ |page=19 |publisher=[[BradyGames]] |isbn=0-7440-0424-1 |access-date=March 27, 2011}}</ref> '' Space Invaders'' also adopted the multi-chip [[barrel shifter]] circuit first developed by Midway for ''Gun Fight'', which had been a key part of that game's smoother animation. This circuit allowed the 8080 CPU to shift pictures in the graphics framebuffer faster than it could using only its own native instructions.<ref>In ''Gun Fight'', the bit-shifts performed by this circuit appear on the screen as horizontal offsets. The circuit in ''Space Invaders'' works the same, but the bit shifts it does are now '''vertical''' from the player's perspective because the entire screen has been rotated by 90 degrees.</ref>

Despite the specially developed hardware, Nishikado was unable to program the game as he wanted—the Control Program board was not powerful enough to display the graphics in color or move the enemies faster—and considered the development of the hardware the most difficult part of the process.<ref name="GI-177" /><ref name="Edge-Taito" /> While programming, Nishikado discovered that the processor was able to [[Rendering (computer graphics)|render]] each frame of the alien's animation graphics faster when there were fewer aliens on the screen. Since the alien's positions updated after each frame, this caused the aliens to move across the screen at an increasing speed as more and more were destroyed. Rather than design a compensation for the speed increase, he decided that it was a [[feature, not a bug]], and kept it as a challenging [[gameplay]] mechanism.<ref name="RG-3" />

Taito released ''Space Invaders'' in July 1978.<ref name="FT"/> They released both an [[Arcade cabinet#Upright cabinets|upright arcade cabinet]] and a so-called [[Arcade cabinet#Cocktail cabinets|"cocktail-table" cabinet]]; following its usual practice, Taito named the cocktail version ''T.T. Space Invaders'' ("T.T." for "table-top"). Midway released its upright version a few months later and its cocktail version several months after that. The cabinet artwork featured large [[humanoid]] [[monster]]s not present in the game; Nishikado attributes this to the artist basing the designs on the original title of "''Space Monsters''", rather than referring to the actual in-game graphics.<ref name="GI-177" /> In the upright cabinets, the graphics are generated on a hidden CRT monitor and reflected toward the player using a [[semi-transparent mirror]], behind which is mounted a plastic cutout of a [[Natural satellite|moon]] bolted against a painted starry background. The backdrop is visible through the mirror and thus appears "behind" the graphics.<ref name="RG-41" /> Both Taito's and Midway's first Space Invaders versions had black-and-white graphics with a transparent colored overlay using strips of orange and green [[cellophane]] over certain portions of the screen to add color to the image. Later Japanese releases used a rainbow-colored cellophane overlay,<ref name="RG-41" /> and these were eventually followed by versions with a color monitor and an electronically generated color overlay.<ref name="RG-41" />