Editing Asteroids (video game) (section)

==Development==
''Asteroids'' was conceived by Lyle Rains and programmed by Ed Logg with collaborations from other Atari staff.<ref name="allgame">{{Cite web | url=http://www.allgame.com/game.php?id=15438 | work=allgame | publisher=Macrovision | title=Asteroids | author=Brett Alan Weiss | access-date=June 6, 2009 | archive-url=https://web.archive.org/web/20090308030532/http://www.allgame.com/game.php?id=15438 | archive-date=March 8, 2009}}</ref> Logg was impressed with the Atari Video Computer System (later called the [[Atari 2600]]), and he joined Atari's coin-op division to work on ''Dirt Bike'', which was never released due to an unsuccessful field test. Paul Mancuso joined the development team as ''Asteroids''{{'}} technician and engineer Wendi Allen contributed to the hardware.<ref name="EdgeAsteroids"/> During a meeting in April 1979, Rains discussed ''Planet Grab'', a multiplayer arcade game later renamed to ''Cosmos''. The unfinished game featured a giant, indestructible asteroid.<ref name="RetroGamerAsteroids"/>  Logg did play Cosmos and remembered shooting the indestructible asteroid to no effect.  So Rains asked Logg: "Well, why don't we have a game where you shoot the rocks and blow them up?" In response, Logg described a similar concept where the player selectively shoots at rocks that break into smaller pieces.<ref name="ClassicGamingAsteroids">{{cite web|url=http://classicgaming.gamespy.com/View.php?view=GameMuseum.Detail&id=25 |title=Asteroids |author=William Cassidy |work=ClassicGaming |publisher=IGN |access-date=January 6, 2014 |url-status=dead |archive-url=https://web.archive.org/web/20121029030926/http://classicgaming.gamespy.com/View.php?view=GameMuseum.Detail&id=25 |archive-date=October 29, 2012 |df=mdy}}</ref> Thus combining the two-dimensional approach of ''Space War'' with ''Space Invaders''{{'}} addictive gameplay of "completion" and "eliminate all threats".<ref name="RetroGamerAsteroids"/>  Both agreed on the concept.<ref name="RetroGamerAsteroids"/>

===Hardware===
''Asteroids'' was implemented on hardware developed by Allen and is a [[vector monitor|vector game]], in which the graphics are composed of lines drawn on a vector monitor.<ref name="allgame"/> Rains initially wanted the game done in [[raster graphics]], but Logg, experienced in [[vector monitor|vector graphics]], suggested an XY monitor because the high image quality would permit precise aiming.<ref name="RetroGamerAsteroids"/><ref name="EdgeAsteroids"/> The hardware is chiefly a [[MOS Technology 6502|MOS 6502]] executing the game program,<ref name="RacingTheBeam">{{cite book |last1=Monfort |first1=Nick |last2=Bogost |first2=Ian |title=Racing the Beam |publisher=[[MIT Press]] |year=2009  |name-list-style=amp|title-link=Racing the Beam|isbn = 9780262261524}}</ref> and [[QuadraScan]], a high-resolution vector graphics processor developed by Atari and referred to as an "XY display system" and the "Digital Vector Generator (DVG)".<ref name="WiredEdLogg"/><ref>{{cite book |last=Dillion |first=Roberto |title=The Golden Age of Video Games: The Birth of a Multibillion Dollar Industry |publisher=CRC Press |year=2011 |page=58 |chapter=Part 1: Games That Pushed Boundaries |isbn=978-1-4398-7323-6}}</ref><ref name="asteroidsflyer">Asteroids Flyer, 1979, Atari, Inc.</ref>

The original design concepts for QuadraScan came out of Cyan Engineering, Atari's off-campus research lab in [[Grass Valley, California]], in 1978. Cyan gave it to Wendi Allen, who finished the design and first used it for ''Lunar Lander''. Logg received Allen's modified board with five buttons, 13 sound effects, and additional RAM, and he used it to develop ''Asteroids''. The size of the board was 4 by 4 inches, and it was "linked up" to a monitor.<ref name="WiredEdLogg"/><ref name="RetroGamerAsteroids"/>

===Implementation===
Logg modeled the player's ship, the five-button control scheme, and the game physics after ''Spacewar!'', which he had played as a student at the [[University of California, Berkeley]], but made several changes to improve playability. The ship was programmed into the hardware and rendered by the monitor, and it was configured to move with thrust and inertia.<ref name="WiredEdLogg"/><ref name="RetroGamerAsteroids"/><ref name="RulesOfPlay"/> The hyperspace button was not placed near Logg's right thumb, which he was dissatisfied with, as he had a problem "tak[ing] his hand off the thrust button".<ref name="RetroGamerAsteroids"/> Drawings of asteroids in various shapes were incorporated into the game.<ref name="EdgeAsteroids"/> Logg copied the idea of a high score table with initials from Exidy's ''[[Star Fire]]''.<ref name="RetroGamerAsteroids"/>

The two saucers were formulated to be different from each other. A steadily decreasing timer shortens intervals between saucer attacks to keep the player from not shooting asteroids and saucers.<ref name="RetroGamerAsteroids"/> A "heartbeat" soundtrack quickens as the game progresses.<ref name="AtariIncBIF">{{Cite book |last1=Vendel |first1=Curt |last2=Goldberg |first2=Marty |title=Atari Inc.: Business Is Fun |publisher=Syzygy Company Press |date=November 2012 |orig-year=1st. Pub. 2012|page=515 |chapter=Chapter 8 |isbn=9780985597405 |chapter-url=https://books.google.com/books?id=3FwGMtRafrAC&q=asteroids+heartbeat&pg=PA515 |name-list-style=amp}}</ref> The game does not have a sound chip. Allen created a hardware circuit for 13 sound effects by hand which was wired onto the board.<ref name="RetroGamerAsteroids"/>

A prototype of ''Asteroids'' was well received by several Atari staff and engineers, who "wander[ed] between labs, passing comment and stopping to play as they went". Logg was often asked when he would be leaving by employees eager to play the prototype, so he created a second prototype for staff to play.<ref name="RetroGamerAsteroids"/><ref name="ClassicGamingAsteroids"/> Atari tested the game in arcades in [[Sacramento, California]], and also observed players during focus group sessions at Atari. Players used to ''Spacewar!'' struggled to maintain grip on the thrust button and requested a joystick; players accustomed to ''[[Space Invaders]]'' noted they get no break in the game. Logg and other engineers observed proceedings and documented comments in four pages.<ref name="RetroGamerAsteroids"/>
<!-- HIDDEN BECAUSE OF NO EASY RELIABLE SOURCE: ''Asteroids'' uses 6 [[kilobyte|KB]] of [[Read-only memory|ROM]] code. Another 2 KB of vector ROM contains the descriptions of the main graphical elements (rocks, saucer, player's ship, explosion pictures, letters, and digits) in the form of DVG commands. For each picture frame, the 6502 writes graphics commands for the DVG into a defined area of [[RAM]] (the vector RAM) and then asks the DVG to draw the corresponding vector image on the screen. The DVG reads the commands and generates appropriate signals for the vector monitor. There are DVG commands for positioning the cathode ray, for drawing a line to a specified destination, calling a subroutine with further commands, and so on. It features various sound effects, each of which is implemented by its own circuitry. There are seven distinct audio circuits designed by Delman. The CPU activates these audio circuits (and other hardware components) by writing to special memory addresses (memory mapped ports). The inputs from the player's controls (buttons) are also mapped into the CPU [[address space]]. -->

===Quirks===
''Asteroids'' slows down as the player gains 50–100 lives, because there is no limit to the number of lives displayed. The game's code continues trying to draw them even if they fall outside the boundaries of the screen. After more than 250 lives are collected, the game slows down enough that the [[watchdog timer]] thinks it has crashed and reboots the hardware.<ref name="EdgeAsteroids"/>

There is a limit of 26 asteroids. If there are already that many, shooting a large asteroid turns it into a single medium one, rather than two as per normal.  Similarly, a medium asteroid turns into a single small one instead of splitting.<ref name="ArcadeHistory">{{cite web | url = https://www.arcade-history.com/?n=asteroids-upright-model&page=detail&id=126 | title = Asteroids [Upright model], the Arcade Video game | author = Arcade-History/Gaming-history | date = 2025 | access-date = 2 Jan 2025 | language = en | quote = The game program only allows 26 asteroids on the screen at any one time. … | at = "Tips and Tricks" section}}</ref>
<!-- HIDDEN BECAUSE OF LACK OF RELIABLE SOURCE: On some early versions of the game, it was also possible to hide the ship in the score area indefinitely without being hit by asteroids.<ref>[http://www.atari800xl.org/asteroids/ Atari 800XL]</ref> -->