Editing Defender (1981 video game) (section)

== Development ==
[[File:EugeneJarvis cax2006 brighter.jpg|thumb|alt=A man with short dark hair in a pink shirt, speaking into a microphone in his right hand.|[[Eugene Jarvis]], a pinball programmer at the time, headed development of ''Defender''.]]

''Defender'' was Williams Electronics' first attempt at developing a new video game; the company's earlier game was a ''[[Pong]]'' clone.<ref name="Ultimate"/> The popularity of coin-operated arcade games in 1979 spurred the company to shift its focus from pinball games to arcade games.<ref name="Halcyon">{{cite book| title = Halcyon Days: Interviews with Classic Computer and Video Games Programmers| editor = James Hague| year = 1997| chapter = Eugene Jarvis| publisher = Dadgum Games| chapter-url = https://dadgum.com/halcyon/BOOK/JARVIS.HTM| access-date = 2009-12-06| title-link = Halcyon Days (book)}}</ref> The company chose Eugene Jarvis, who had a successful record of Williams pinball games, to head development.<ref name="Ultimate"/> [[Larry DeMar]], Sam Dicker, and Paul Dussault assisted Jarvis.<ref name="Gamasutra-Defender">{{cite web| url = http://www.gamasutra.com/view/feature/4078/the_history_of_defender_the_joys_.php| archive-url = https://web.archive.org/web/20090715221924/http://www.gamasutra.com/view/feature/4078/the_history_of_defender_the_joys_.php| url-status = dead| archive-date = July 15, 2009| title = The History of Defender: The Joys of Difficult Games| website = Gamasutra| first = Matt| last = Barton|author2=Bill Loguidice| date = 2009-07-14| access-date = 2009-12-06}}</ref> At the time, Williams had a small staff and the management was unfamiliar with technology used for its electronic games. As a result, the staff was afforded a large amount of creative freedom.<ref name="Halcyon"/>

=== Initial development ===
Space was a popular setting for video games at the time, and Jarvis felt the abstract setting would help obscure simple graphics that lacked realism.<ref name="Ultimate"/> Initially, Jarvis spent 3–4&nbsp;months developing color variations of [[Taito]]'s ''[[Space Invaders]]'' and [[Atari, Inc.]]'s ''[[Asteroids (video game)|Asteroids]]''.<ref name="Arc-Treasure-1">{{cite video game| title= [[Midway Arcade Treasures]]| developer= [[Backbone Entertainment|Digital Eclipse]]| publisher= [[Midway Games]]| date= 2003-11-18| platform= [[PlayStation 2]]| level= The Inside Story On Defender}}</ref> First inspired by ''Space Invaders'', he created a similar game with new gameplay mechanics. After spending a few weeks on the design, however, the team abandoned the idea, believing it lacked enjoyment. Development then shifted to emulating Atari's ''Asteroids'', but hardware differences between ''Asteroids'' and ''Defender''{{'}}s proposed specifications were problematic. ''Asteroids'' displays [[vector graphics]] on a special monitor, while the staff planned to use pixel graphics on a conventional monitor. The team experimented with recreating the game with pixel graphics, but also abandoned it because they felt the gameplay lacked enjoyment and visual appeal.<ref name="RG-55"/>

Believing their first attempts to be too derivative, the developers held brainstorming sessions. During a session, they agreed that one of ''Asteroids''{{'}}s favorable elements was its [[Wraparound (video games)|wraparound]].<ref name="RG-55"/> They felt a game that allowed the player to fly off the screen would be exciting and decided to create a game world larger than the screen displayed. The game's environment was made longer than the screen and scrolled horizontally.<ref name="Ultimate"/><ref name="RG-55"/> Expanding on the idea, they envisioned a version of ''Space Invaders'' rotated 90&nbsp;[[Degree (angle)|degrees]]. By changing the orientation of ''Space Invaders''{{'}} design, the ship moved up and down while flying horizontally. Large asteroids, an element from ''Asteroids'', were then added to the game world, but were later removed because the staff felt it lacked enjoyment.<ref name="RG-55"/> Jarvis intended the screen to scroll only from left to right; fellow Williams employee [[Steve Ritchie (pinball designer)|Steve Ritchie]], however, convinced him the game should be able to scroll in either direction.<ref name="Ultimate"/><ref name="RG-55"/>

After six months of development, the team felt the game had not made enough progress. They examined other games and concluded that survival was a necessary component to implement. To achieve this, they devised enemies to present a threat, the first of which was the "Lander".<ref name="RG-55"/> Jarvis enjoyed violent, action entertainment, and wanted the game to have those elements, but felt the action should have a reasonable objective. Inspired by the 1960s television show ''[[The Defenders (1961 TV series)|The Defenders]]'', Jarvis titled the game ''Defender'', reasoning that the title helped justify the violence.<ref name="Ultimate"/> He added astronauts to expand on the space theme and give players something to defend while they shot enemies.<ref name="Ultimate"/><ref name="RG-55"/> The element of flying over a planetscape was added after a brainstorming session between Jarvis and Ritchie.<ref name="Joystik1">{{cite journal| journal = JoyStik| title = Interview: Eugene Jarvis|date=September 1982| page = 7|issue = 1}}</ref> The landscape is depicted as a line only a pixel wide, primarily because the hardware was not powerful enough to generate anything more detailed.<ref name="RG-55"/>

=== Later development ===
By July, development was behind schedule and Jarvis's superior began to pressure him to finish the game in time for a then-upcoming trade show, the AMOA, in September. Jarvis spent several weeks creating the astronauts, which his boss felt should be omitted if the process didn't speed up. The pressure frustrated him to the point he considered resigning. Around that time, a new programmer named Sam Dicker was hired.<ref name="Ultimate"/> He assisted in programming the game and added visual and audio effects.<ref name="Ultimate"/><ref name="RG-55"/> For example, Dicker implemented a particle effect [[algorithm]] to generate unique explosions for destroyed enemies.<ref name="RG-55"/> The new elements re-invigorated Jarvis, who felt the project began to show promise.<ref name="Ultimate"/>

Development then shifted focus to the enemies. Landers were given the ability to capture humans, and a new enemy was devised from the mechanic: "Mutants", captured humans that had turned hostile. The Mutants added a rescue element to the game that Jarvis believed made it more interesting to players and encouraged them to continue playing. The element of making a "comeback" from a dire situation was applied to the planet as well. Jarvis felt it mimicked the ups and downs of real life. "Bombers", enemies which release floating bombs on the screen, were added next. More enemies were added to create different gameplay elements. "Swarmers" and "Pods" were designed to attack the spaceship as opposed to the astronauts. "Baiters" were included to add pressure to the player by preventing them from lingering. The enemies quickly follow the spaceship to collide with it, and were based on a similar enemy in ''Asteroids''.<ref name="RG-55"/>

By September, the game was still unfinished, and almost every Williams programmer assisted in meeting the deadline for the AMOA trade show.<ref name="Ultimate"/><ref name="GS-Hall">{{cite web| url = http://archive.gamespy.com/halloffame/may01/defender/| title = Hall of Fame: Defender| publisher = [[GameSpy]]| first = David| last = Cuciz| date = May 2001| access-date = 2009-12-06 |url-status=dead |archive-url=https://web.archive.org/web/20050112002131/http://archive.gamespy.com/halloffame/may01/defender/ |archive-date=2005-01-12}}</ref> The evening before the trade show, the arcade cabinets were delivered for display.<ref name="Arc-Treasure-1"/> The developers, however, forgot to create an [[attract mode]] (an automated sequence designed to entice an audience to play) and high score system for the game, and began working on them that night. DeMar coded the attract mode, Dussault and Dicker created the high score table, and Jarvis [[playtested]] and fixed bugs.<ref name=NGen38>{{cite magazine |title=Are You a Hardcore Gamer? |magazine=[[Next Generation (magazine)|Next Generation]]|issue=38|publisher=[[Imagine Media]] |date=February 1998|pages=47–48}}</ref> Early the next morning, the team created the final [[EPROM]] chips for the mode and installed them in a cabinet. The chips were put in backwards, causing an [[electrical short]] when the cabinet was turned on, so the team had to quickly burn a new set of EPROMs.<ref name=NGen38/> Once the attract mode was operational, Jarvis and the team returned to their homes to prepare for the show.<ref name="Fever"/> After the show, the developers expanded the game to allow users to play indefinitely. The display model featured five levels, which the team felt was more than enough because of the game's difficulty. Most Williams employees could not progress past the third level and Jarvis's score of 60,000&nbsp;points seemed unbeatable to them. The developers decided it was best to be prepared for players that might exceed their expectations and added more levels that repeated.<ref name="Arc-Treasure-1"/>

=== Hardware ===
The game features amplified [[monaural]] sound and [[Raster graphics|pixel graphics]] on a [[Cathode-ray tube|CRT monitor]]. A [[Motorola 6809]] [[central processing unit]] handles the graphics and gameplay, while a [[Motorola 6800]] microprocessor handles the audio.<ref name="KLOV">{{cite web| url = http://www.klov.com/game_detail.php?game_id=7547| title = Defender - Videogame by Williams (1980)| publisher = [[Killer List of Videogames]]| access-date = 2009-12-06}}</ref> A pack of three [[AA battery|AA batteries]] provide power to save the game's settings and high scores when the machine is unplugged from an electrical outlet. The cabinet artwork is stenciled on the wooden frame.<ref name="PriceGuide-1">{{cite book| title = Official Price Guide to Classic Video Games| first = David| last = Ellis| pages = [https://archive.org/details/officialpricegui00davi/page/337 337–340]| chapter = Arcade Classics| publisher = [[Random House]]| isbn = 0-375-72038-3| year = 2004| chapter-url = https://archive.org/details/officialpricegui00davi| url = https://archive.org/details/officialpricegui00davi/page/337}}</ref>

Development started by focusing on the game's hardware. The staff first debated what type of monitor to use: black-and-white or color. They reasoned that using advanced technology would better establish them as good designers and chose a color monitor. The developers estimated that the game would require 4&nbsp;colors, but instead chose hardware that could display each pixel in 16&nbsp;colors. At the time, the designers believed that was more than they would ever need for a game.<ref name="Ultimate"/> The monitor's resolution is 320×256, an expansion from the then-industry standard of 256×256. The staff believed that the wider screen provided a better aspect ratio and would improve the game's presentation.<ref name="RG-55">{{cite magazine|magazine= [[Retro Gamer]]| publisher = [[Imagine Publishing]]| title = The Making of Defender| issue = 55| pages = 34–39|date=October 2008}}</ref> Video games at the time relied on hardware to animate graphics, but the developers decided to use software to handle animation and programmed the game in [[assembly language]].<ref name="Halcyon"/><ref name="RG-55"/> The switch allowed them to display more on-screen objects at a lower cost.<ref name="RG-55"/>

The game's control scheme uses a two-way joystick and five buttons. Jarvis designed the controls to emulate both ''Space Invaders'' and ''Asteroids'' simultaneously. The player's left hand manipulates the joystick similar to ''Space Invaders'' and the right hand pushes buttons similar to ''Asteroids''. The button functions to shoot projectiles and accelerate use a similar layout to ''Asteroids''. Jarvis reasoned that players were accustomed to the control schemes of past games and felt altering past designs would prove difficult for them.<ref name="RG-55"/>