Random and Raster: Display Technologies and the Development of Videogames

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As Published http://dx.doi.org/10.1109/MAHC.2009.50

Publisher Institute of Electrical and Electronics Engineers

Version Final published version

Citable link http://hdl.handle.net/1721.1/60006

Terms of Use Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. Random and Raster: Display Technologies and the Development of Videogames

Nick Montfort Massachusetts Institute of Technology

Ian Bogost Georgia Institute of Technology

Videogame developers have utilized many types of display technology, from oscilloscopes to Teletypes to high-definition LCD displays. Two significant early display technologies, raster scan and random scan CRTs, played a significant part in the history and evolution of videogames. A study of these technologies shows how the choice of one or the other, and the need to port games between the two, influenced game design and prompted developers to innovate.

Many forces have shaped the development of programmer writing a game for a PDP-1 videogame displays and influenced the design would have assumed that a text-output video and functionality of games, not just their terminal or Teletype machine would be ready appearance. The videogame display technolo- at hand, and a coin-operated (coin-op) arcade gies that were put to use, and the extent game creator might have some flexibility in to which they were used, had a great deal to choosing a particular type or orientation of do with convenience and the ability to source monitor in the cabinet. No matter the type, dis- display components. Since early videogame play technologies have exerted a strong influ- implementations, resolutions have increased, ence on the evolution of videogames. bulky video picture tubes have given way From the end of the 1970s through the to widescreen flat-panel LCD displays, and 1980s, two fundamentally different display increased computing power has allowed technologies were in use side by side in real-time 3D graphics to replace 80-column arcades. The raster-scan display, which worked text displays. Conventional wisdom might as- similarly to the pre-flat-screen TV (an electron sume that such changes amount to simple beam swept across and down the screen to technological improvements. draw the image), was used in Space Invaders, Looking back over the history of gaming, Berzerk, Pac-Man, Donkey Kong, Robotron: 2084, however, reveals that different display technol- and many other coin-ops. Other systems used ogies have exerted creative force on the devel- random-scan displays (also called vector graph- opment of specific videogames. During the ics, stroke writing, and calligraphic), which ar- last half-century, very different display tech- bitrarily pointed an electron gun. Atari used nologies have provided the ‘‘video’’ in video- this technology, calling it XY graphics, when games. For example, the very early game it developed Tempest, Battlezone, Asteroids,and Tennis for Two used an oscilloscope, and early Lunar Lander. (See the sidebar for more details text adventures played on minicomputers about specific games.) often used a Teletype or other print terminal In this article, we describe some of the in- to print output on paper. Sometimes the dis- teraction between early videogame develop- play technology was imposed by the game ment and display technologies, considering play. For example, videogames played in the the influence of XY graphics in contrast to home typically can’t rely on expensive or un- the more familiar raster-scan system. In the usual displays, so an ordinary television is usu- 1970s, both random and raster displays ally the most sensible display choice. But a were commonly used in many applications,

34 IEEE Annals of the History of Computing Published by the IEEE Computer Society 1058-6180/09/$26.00 c 2009 IEEE Further Reading on Videogame History We have not individually cited each well-known and References well-documented historical fact (such as the release years of popular videogames) because such detail is outside the 1. V. Burnham, Supercade: A Visual History of the scope of this article. For general information on videogame Videogame Age 19711984, MIT Press, 2003. history, we suggest several books.15 There are also helpful 2. R. DeMaria and J. Wilson, High Score!: The resources easily found online, such as the longstanding Illustrated History of Electronic Games, Osborne/ Killer List of Videogames (http://www.klov.com) and the McGraw-Hill, 2002. project MobyGames (http://www.mobygames.com). 3. W. Forster, The Encyclopedia of Game Machines, Information about the basic functioning of games can be Gameplan, 2005. easily determined by playing the games themselves. 4. S.L. Kent, The Ultimate History of Video Games, Although certain information on the history of video- Prima, 2001. games, both online and in print, might be less than reli- 5. B. Weiss, Classic Home Video Games, 19721984, able, basic information about which companies and programmers developed popular games is not usually McFarland, 2007. in dispute. and XY graphics systems presented them- The electron beam does not sweep across the selves as viable candidates for adoption in screen from left to right, being turned on coin-op games like Asteroids and Star Castle. and off as it makes its way down and then Often, random-scan types of displays offered returns back to the top 60 times each second. a kind of high-resolution graphics unavail- Instead, the electron gun is pointed at a cer- able in raster displays—for example, by tain location, turned on, and moved from smoothly scaling and rotating graphics in a that (x, y) coordinate to another point in a way that would otherwise have been diffi- straight line, where it is turned off again. An cult, if not impossible. oscilloscope functions similarly; it just deflects Gaming brought both displays to a broad the electron beam using electrostatic force. XY public and into contact with one another, monitors use magnetic force. along with new constraints. Differences be- Just as a storage device that is arbitrarily ac- tween the two systems meant that developers cessible offers random access, random scan porting popular random-scan coin-op titles uses a beam that can be made to move any- were forced to deliberately evaluate game ele- where. Such systems directly draw lines in ments, sometimes devising entirely new an (x, y) coordinate system. Raster-graphics approaches to similar high-level game con- systems, on the other hand, draw a grid of cepts. When games that originally used vec- data representing a pattern of pixels. If the tor displays were ported to raster-based correspondence between bits and pixels is home systems, the practical differences be- one to one, the data is a bitmap; more gener- tween the display technologies were revealed ally, such data is a pixmap (p. 13).1 As a result, in a particularly interesting way—for exam- it is possible to render detailed bitmapped ple, this is the case with the home version images on a raster system, but a vector system of Asteroids, developed for the Atari VCS makes it much easier to scale, shear, and ro- (a.k.a. Atari 2600), and the Atari VCS game tate shapes that have been drawn with the Yars’ Revenge, which was inspired by Star Cas- primitives of that system. tle. By looking at Yars’ Revenge and Asteroids In the 1980s, other differences between in detail, we can see how developers modi- the two types of displays included the acces- fied the games to account for the different sibility of color and black-and-white raster display systems. Similarly, the home and ar- displays, the better brightness and resolution cade versions of Battlezone and Tempest of vector displays, and the limited number of show how entirely new ways of depicting primitives that could be drawn on a vector the world on screen came about. display before it began to flicker. Videogame systems were not the first to explore the uses Random and raster display of either type of display. Both had been technologies employed in computer graphics for a while Although all early arcade games used CRTs, before commercial videogaming came about, those in vector-graphics games are wired and by the mid-1970s, raster graphics had be- differently than the ones in standard TVs. come dominant (p. 12).2

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The building blocks of Star Castle A hit arcade game would have already had a Programmer Howard Scott Warshaw’s first following, one that might have generated en- assignment at Atari was to port the 1980 thusiasm and an initial market. Even in the vector-graphics arcade game Star Castle, pro- early days of videogaming, when the arcade duced by Cinematronics, to the Atari VCS. hits were Pong and Tank rather than Pac- He told an interviewer, ‘‘I soon realized that Man, an arcade game’s fan following was im- a decent version couldn’t be done, so I took portant when it came to the home console what I thought were the top logical and geo- market. Given the differences in platform metric components of Star Castle and reor- and the need to rewrite each game from ganized them in a way that would better scratch, a port to the Atari VCS had plenty suit the machine.’’3 of room to become a fairly involved adapta- Warshaw’s comment reveals how the plat- tion rather than a straightforward re-creation. form participates in the ecology of game This could leave some arcade game fans dis- development. The design of the resulting appointed, as happened with Pac-Man. game, Yars’ Revenge (1981), was not entirely Cinematronics, the developer of Star Cas- determined by the Atari VCS, nor was it tle, was the first company to release an arcade dropped on the platform by its programmer game that used the XY graphics display tech- with no concern for how the system worked. nology: Space Wars (1977). Like the first ras- The original idea was to imitate another ter arcade game, Nolan Bushnell’s pre-Atari game, but the capabilities and limitations of Computer Space,itwasatwo-playerarcadeim- the Atari VCS led the developer to create plementation of the 1962 PDP-1 program something different. Specifically, the result Spacewar.2 Star Castle had significantly differ- was a reorganization of Star Castle’s major ent game play and was developed by a differ- components that recognized the differences ent person, but the space setting and control between vector and raster graphics, exploited scheme showed a clear connection to Space the abilities of the Atari VCS graphics system, Wars.5 and was well-suited to home play. Vector-graphics systems have certain The Atari VCS has a graphics system that advantages over raster-graphics systems—at was unusual even for the time. To keep least, they did in the late 1970s and early costs down, the unit lacked a frame buffer, 1980s. Specifically, it is easier to rotate shapes a memory region in which the screen image and scale them up or down on a vector sys- could be set up and blitted across automati- tem, as is necessary when zooming in or cally. Instead, programmers had to write out. For instance, to resize an object that is code that would set up each individual scan centered on (0, 0) and consists of some set line for the television interface adapter of lines, each endpoint’s coordinates can sim- (TIA). The registers for two player sprites, ply be multiplied by the scaling factor. It does two one-pixel missiles, one one-pixel ball, not get much trickier when the object is cen- and the playfield had to be ready on each tered elsewhere or when there should be dif- line of the screen so the electron beam ferent amounts of scaling in the horizontal would have the appropriate objects ready to and vertical axes. It is also straightforward draw. For this reason, the challenge of pro- to shear a shape, keeping one axis constant gramming the Atari VCS was sometimes re- while shifting the other. Rotation, scaling, ferred to as ‘‘racing the beam.’’ and shear are the basic linear transforma- Warshaw explained in another interview tions, and all can be accomplished by sub- how radical it was for Atari to drop Star jecting the coordinates of a shape’s points Castle, which the company had already to a single matrix multiplication. In combi- arranged to license: nation with translation (the displacement of the shape in space, which only requires add- I did something no one else had ever done, I ing the distance to be translated), these allow went to my boss and said that I had an idea for all the possible transformations that keep for an original game that would use the straight lines straight. same basic play principles of Star Castle but In a raster-graphics system, the only feasi- was designed to fit the VCS hardware so it ble way to show an object’s rotation is to dis- wouldn’t suck. And to their credit, they let me go with it. Think about that. They blew play a different bitmap—a hard-coded image off a license to let me pursue an original con- of the shape rotated by the desired amount. cept with the promise of making a better This is how tanks and planes in the Atari game for the system. That would never hap- VCS game Combat are rotated, for instance. pen today.4 A simple form of scaling is supported in

36 IEEE Annals of the History of Computing hardware, via the TIA’s specialized number- size registers, but smoother zooming has to be done with new graphics. Even when XY Asteroids’ arcade graphics hardware is not used, these benefits of vector graphics can be seen when compar- original and Atari VCS ing software platforms, such as an early version of the bitmap-based Macromedia port reveal how Director and an early version of Macro- media’s vector-graphics Flash environment. different display Vector-graphics games used the special capabilities of the display system to good technologies predispose effect. Battlezone is a classic example of a game that uses the scaling capability to designers to develop make tanks larger, so that they appear to be approaching. Asteroids, on the other hand, different sorts of games. makes more prominent use of the rotation facility. and fire, and a hyperspace button that is set The smash hit Asteroids below the others—exactly the same five but- The original Asteroids arcade game, devel- tons as on Space Wars. Star Castle had the first oped by Ed Logg and based on a concept by four controls, but not the hyperspace button. Lyle Rains, was released in 1979. Other hit In Asteroids, the monitor is oriented horizon- games that year were Atari’s first vector- tally and the playing field’s topology is that graphics game, Lunar Landar,andNamco’s of a torus: objects wrap around vertically hit game Galaxian. The arcade Asteroids is in- and horizontally. This is the same as in Star teresting to compare to its Atari VCS port, Castle and is one option that can be selected which came out in 1981, the same year that in Space Wars. Yars’ Revenge came out for that console. One difference between Star Castle and the This comparison demonstrates how a game arcade Asteroids is the color overlays, which can have a different appearance and function place the central cannon in a circle of yellow when it is created for a raster instead of a vec- and the protective shield around it in a ring tor display. of red. (Color overlays were not used exclu- Although the ship can move freely about sively on XY games; Space Invaders cabinets the screen in Asteroids, the game is organized had them, too.) Asteroids lacked such colored radially around the ship, which must be the transparencies. The game originally used a player’s center of attention and which can ro- monochrome monitor, the Electrohome tate and fire shots in all directions. With its G05-801, a 19" monitor made by Wells- space setting, its rotating and firing ship, Gardner Electronics and previously used in and its controls, Asteroids also shares several Lunar Lander (p. 9).6 Without overlays, an fundamental qualities with Spacewar, Space image on this monitor appears as white Wars,andStar Castle. lines on black. The asteroids are drawn Brad Stewart, who had earlier ported more dimly, and move about in arbitrary Breakout to the Atari VCS after winning the directions. The ship and flying saucers are right to port the game by besting a fellow drawn more brilliantly, and the shots fired programmer in the arcade Breakout,wenton from either are particularly luminous points. to develop the VCS Asteroids. Both the VCS These aspects—along with high contrast, game and the coin-op game purport to be sharp lines, and a fast refresh rate—make Asteroids, and they feature a rotating ship, Asteroids visually impressive in a way that is rocks breaking up into smaller rocks, and fly- hard to imagine when looking at an emula- ing saucer enemies. The arcade game uses the tor, screen shot, or diagram. capabilities of the vector display beautifully A player can immediately recognize the and works well in the situation of the arcade, VCS Asteroids as a version of the arcade while the cartridge exhibits classic VCS qual- game. It boasts similar game play, visual ap- ities that connect to home gaming traditions pearance, and sound. The minor differences and the TIA’s affordances. are telling, however. The asteroids are filled- Players use five buttons to control the ar- in and sometimes flickering masses that are cade Asteroids: a pair for rotating clockwise drawn in different colors rather than as or counterclockwise, a pair to control thrust monochrome outlines—assuming that the

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candoinastraightforwardway.Themotion of the asteroids is also telling. On the random-scan display, their vectors of movement are random—any direction is possible. On the left-to-right sweeping raster display of the TV, there is a predisposition to up-or- down motion because the asteroids cannot move horizontally.

From a port to Yars’ Revenge The object of Star Castle is to destroy the rotating cannon in the center of the screen repeatedly, using a triangular, rotating ship that looks and moves like the ones in Aste- roids and Space Wars. The enemy cannon appears behind colored overlays and is sur- rounded by three concentric, rotating shields, each of which is made of line segments. The segments can be destroyed by fire from the player’s ship, but whenever an entire ring is shot away, it regenerates. When- ever the player clears a path to the cannon, creating a chance to shoot at it to destroy it, the cannon fires a large missile toward the player’s ship. As the player is trying to break down the shield rings, three mines also move out and seek the player’s ship. They can be avoided or shot, although shooting them does not increase the score and they soon reappear. After a central cannon is finally successfully destroyed, another one quickly Figure 1. Screens shots from (top) Star Castle and (bottom) Yars’ appears with three intact rings around it. Revenge. The inset show details of the two ships and qualities of the Star Castle fared well among the several huge different display technologies used. arcade hits released in 1980 (including Pac- Man, Defender, Centipede, and Missile Com- Atari VCS is set to color and a color TV is used mand), though it didn’t attain as much fame. as a display. The ship is also solid, and it fires In the Atari VCS game inspired by Star Cas- at most two shots at once—not the four that tle, Yars’ Revenge, the player’s ‘‘ship’’ is the are possible in the arcade game. Although Yar, a ‘‘fly simulator’’ that the player controls emulators have been able to make the VCS with a joystick. The game replaces the pivot- Asteroids conveniently available on computers, ing of the ship about a point, which could they use sharp, blocky pixels that were not easily be done by Star Castle’s vector-graphics seen in the same way by players in the early display system, with movement in the stan- 1980s. CRT televisions blur pixels together dard eight directions—up, down, left, right, resulting in something that was clearly differ- and diagonally. The latter form of movement ent from a vector-graphics display, but which was fairly easy for the Atari VCS: translation is also softer and fuzzier than an LCD display.7 while facing in one of eight directions. The The two versions of Asteroids, the arcade Yar sprite is animated, requiring an additional original and the Atari VCS port, reveal how frame for each direction, but its appearance different display technologies predispose facing right is a reflection of what it looks designers to develop different sorts of games. like facing left, allowing some savings. Be- Visually, the solid, colored, blocky rocks of cause up/down reflection is not as straightfor- the VCS version show that the TV is capable ward as left/right reflection on the Atari VCS, of color and that it is at least as easy to the upward-facing and downward-facing Yar make a bitmapped sprite solid as to make it sprites are both laid out in ROM. Switching appear in outline—easier, actually. The differ- between the two requires reading a different ent jags of the arcade Asteroids, defined only bitmap. The insect appearance of the Yar (see by lines, reveal what a vector-graphics system Figure 1) was simply based on what Warshaw

38 IEEE Annals of the History of Computing could draw and animate in an appealing way small entropy pool, one adequate to create within a player sprite. The name Yar was an appropriately irregular visual display. devised by spelling Atari CEO Ray Kassar’s Such an approach takes fewer cycles, but it first name backwards. requires that some random-looking pattern, The objective in Yars’ Revenge is the Qotile, perhaps a fairly large one, be stored in which moves up and down along the right ROM. If such a pattern were to be added, side of the screen and is protected by a shield. something else in the game would have had All the levels are similar in form, but the first to be removed, and there was already less one (and all the odd-numbered levels) have a than a handful of bytes free in the finished stationary, rounded shield around the Qotile, Yars’ Revenge. while the other levels (all the even-numbered Warshaw used the second technique, but ones) feature a block of shield with pieces he made use of a random-looking sequence that move left to right, down a space, right of bytes that would already be laid out in to left, down a space, and then right to left ROM by the time the game was finished—the again through the block. The motion of the game’s code itself—as shown in this 6502 as- pieces mimics that of the CRT’s electron sembly code obtained by disassembling the gun as it sweeps across and back while mov- contents of cartridge ROM:8 ing down the screen. EOR (neutralZonePtr),Y Beyond the basic redesign of the game AND neutralZoneMask play and the graphical advances that were STA PF2 made, there were a few other innovations— AND #$F7 minor, but telling—in Yars’ Revenge.Some STA COLUPF of these, such as the addition of a rudimen- tary pause command, show how game soft- In this part of the neutral zone kernel (the first ware could allow a fixed hardware platform instruction is located at $F084), the values to evolve and suit the needs of home players. pointed to by neutralZonePtr are brought Others demonstrate how some of the lumi- into the accumulator and masked against the nous effects of a vector display game were contents of neutralZoneMask.Thisaccumu- adapted, but not directly translated, into a lator value is used first as the pattern that is raster-graphics display game. loaded into a playfield register and, after it is Yars’ Revenge features a large, four-part dis- masked again, as the playfield color. The play routine that includes one part to draw label neutralZonePtr points to the same ad- the swelling explosion that ends a level; an- dress as does another label, gameTimer.At other to display the score; another to draw this location, a count is stored that is continu- the shield for half the frames of the main ally incremented, once each line, and ranges sequence; and a final one to draw, in alter- over the addresses in cartridge ROM. This pro- nating frames during the main sequence, gression works its way through the code of the the multicolored neutral zone. Although Yars’ Revenge cartridge, with each byte of code the neutral zone and shield bears little resem- being loaded, transformed, and displayed on blance to Star Castle’s spinning, concentric the screen. The bytes in ROM end up being shapes, they create a striking effect that used in three contexts: as executable code, makes use of the console’s different video playfield graphics, and the playfield color. system. When the Qotile is hit, those bytes also supply The neutral zone’s random-looking pat- the random-looking arrangement of the full- terns are not provided by a pseudorandom screen explosion. These effects certainly do number generator—an intricate algorithm not come from Star Castle,andthereisno that, although deterministic, is complex obvious way they could be duplicated on a enough to create a sequence that looks ran- vector-graphics display. dom. Such an algorithm can be implemented Warshaw has explained that he had on the Atari VCS and was used in Activision’s planned to use this method from the start Pitfall, but this programming solution exacts rather than working it out as a solution to a a price in ROM (the code itself must be stored problem that came up: ‘‘It was just a cheap somewhere) and in cycles (the code must be way to get the effect I wanted. I didn’t have run while the game is also carrying out the the time or space to do it any other way.’’5 work of drawing the screen and updating Still, by making the game’s code into an impor- the game state). The alternative is to lay out tant visual component in this raster-specific a random-looking pattern in ROM and sim- way, Warshaw showed how a functioning pro- ply load random-seeming bytes from this gram could shine aesthetically. When players

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tank fighting and set a precedent for Battle- zone. It was also the inspiration for Combat, Vector art paved the the tank game that came with the Atari VCS.9 Earlier, in 1974, two 3D networked games way for modern 3D had been developed. Maze was developed by Greg Thompson, Dave Lebling, and others graphics, suggesting a at MIT and based on work done at NASA Ames. That year, Spasim was also developed way to represent solid by Jim Bowery at the University of Illinois Urbana-Champaign. The former ran on an objects in 3D space Imlac terminal with a vector-graphics display, and the latter used the PLATO-IV’s plasma and animate them display panel. While impressive, these games required tremendous computing resources in real time. and did not reach a large number of players. Although it had these illustrious ances- tors, Battlezone was revolutionary in many look at the neutral zone on the screen, they are ways. The game brought together 2D tank literally looking at the code. Yars’ Revenge motion (along the flat plane of the ground) may not have had any direct influence on with a first-person view onto a 3D world. Bat- the movie Tron, which brilliantly played tlezone not only featured an unusual perspec- with vector- and raster-graphics conventions, tive, it also had an unusual periscope cabinet butthatfilmwasreleasedthesummerafter configuration that let players (if they were Warsaw’s game and features a multicolored, tall enough) place their heads directly against whirling master control program (MCP) that a viewport while others could watch from ei- is cast in a different light by the neutral ther side. Besides the essential elements (3D zone, actually drawn again and again by its opponents and sound effects), the landscape own image, a code-and-data Janus. details included an erupting volcano. Warshaw’s ‘‘original’’ was a brilliant varia- Battlezone found popularity with the mili- tion on Star Castle, played in virtuoso style on tary, which was uncommon for the time. The the Atari VCS. His skill in creating Yars’ Revenge US Army contracted with Atari to develop a is not just seen in his programming chops and modified game to train Bradley Infantry Fight- creativity, but also in his ability to innovate ing Vehicle gunners. This project was contro- and improvise while building down from the versial inside Atari; apparently only two top (an already completed vector-graphics prototypes and a few units were made. Beyond coin-op game with a working game mechanic) this application, Battlezone also entranced a and up from the bottom (a platform that generation of players, some of whom went on offered a particular set of affordances and was to develop other 3D, first-person games. One used in the context of the home). While Aste- young player who particularly enjoyed Battle- roids shows that even a fairly direct arcade zone was John Carmack, who went on to be- port encountered differences in display tech- come the lead programmer at iD Software, nologies, Warshaw’s work exemplifies another the company that pioneered the first-person way of navigating between display technolo- shooter genre with Wolfenstein 3-D (1992), gies and letting the capabilities of the display Doom (1993), and Quake (1996) (p. 20).10 suggest design directions. Adaptations of Battlezone to the Atari VCS again reveal how game developers used raster Zooming through Battlezone affordances differently. Atari’s port, also ti- Ed Rotberg designed Atari’s tank game Bat- tled Battlezone, is an adequate game, but the tlezone (1980) while he was working on 3D tank game that was developed by Activi- another vector-graphics game, Red Baron, sion, Robot Tank (1983), added weather, dif- which let the player fly a biplane and was ferent types of partial damage, and day and released soon after Battlezone. Although the night, all of which use raster-specific effects. plane game offered more degrees of freedom, When the arcade Battlezone tank gets hit, an it didn’t match Battlezone’s popularity as the irregular vector-graphics tree makes it appear first 3D game to reach a mass audience. At as if the glass of the monitor has cracked. the time, tank games were not new; the When the player’s vehicle is destroyed in ei- early, raster-graphics arcade hit Tank,pro- ther Atari VCS game, gray, random shifting ducedbyKeeGames,offeredone-on-one makes the TV screen look like it is losing

40 IEEE Annals of the History of Computing reception and starting to display snow. The player who is preparing to start the game. vector-graphics visual signal for death is ras- When a level is selected, that shape moves to- terized in these two tank games into some- ward the player and the empty spaces between thing more suitable for that display and lines solidify, planes of color filling the tube in more easily accomplished with the console’s a raster-specific way. The player’s ship and the graphics system. early opponents look more or less like vectors, The space trading strategy game Elite, but this changes as the game reveals more pow- released for BBC Micro personal computers erful creatures. The typography is empatheti- in 1984, was notable for using wireframe 3D cally bitmapped and sometimes dissipates graphics with hidden line removal—the lines across the screen. Finally, the game includes a behind surfaces were not drawn so that struc- new type of level, the warp stage, that offers tures appear solid. This technique evolved in rings to fly through and a background that other games, including the Battlezone-like looks like nothing an XY graphics system title Spectre for Macintosh computers, released could produce. in 1991. The line-rendering technique quickly Although Tempest 2000 transforms the ar- evolved from wireframes to filled surfaces to cade original into an updated raster game, it texture-mapped surfaces, which appeared in also hints at the earlier vector-graphics qual- the early 1990s in Wolfenstein 3-D and Ultima ities of Tempest, both to make a connection Underworld. Vector art paved the way for mod- to its arcade inspiration and as a way of evok- ern 3D graphics, suggesting a way to represent ing nostalgia for the random-scan tubes of solid objects in 3D space and allowing the de- years past. The game shows that although a velopment of feasible methods to animate TV cannot convincingly imitate a vector- such objects in real time. Today, 3D polygons graphics display, it can be made to remediate are rasterized for display in pixel form on a such graphics and remind the player of the modern computer or TV monitor, but the original display system, rather than com- basic way that shapes appear in 3D space pletely replacing the vector idiom with a ras- could already be seen by players zooming ter one, as with Yars’ Revenge and Asteroids. through Battlezone’s vector landscape. Raster and random, bitmap and vector Tempest turning Videogames of the late 1970s and early Tempest, designed by Atari’s Dave Theurer 1980s are strongly associated with vector and released in 1981, used a different sort of graphics. In recent years, we have seen a monitor: the Wells-Gardner 6100 Quadras- trend to re-create this ‘‘vector look’’ in con- can, a color display with three beams for temporary games that are made to seem red, blue, and green. Along with Atari’s retro. New commercial games have been cre- Space Duel, Tempest was in the first wave of ated that borrow the geometric appearance of color vector-graphics games. The game also vector graphics even though they are not allowed players to choose the level where played on XY displays. The most commer- they wanted to begin; this poor man’s con- cially successful of these titles is Geometry tinue feature let more capable players jump Wars, originally an Xbox shooter released in to more challenging levels, while novices 2003 that combines the simple geometric could select an easier stage. In addition, Tem- shapes of games like Asteroids with psyche- pest offered differently shaped levels, so that delic shader effects afforded by modern 3D the terrain and the challenges varied as the graphics acceleration. In games like Geometry player progressed. Wars, the use of a simple triangular ship and To allow the game’s monsters to move abstract geometric enemies references the around, Tempest took advantage of the ease game’s vector predecessors. Other games, with which objects can be rotated in an XY such as Tempest 2000 developer Jeff Minter’s framework. It used scaling to make it appear Xbox 360 game Space Giraffe, released in that enemies were moving forward and grow- 2008, borrow the tube shooter dynamics ing larger. And as those enemies moved over descended from Tempest but use vector-style uneven terrain, Tempest exploited the XY lineartasonlyasmallpartofthevisuals, graphics hardware’s ability to shear the which include 3D shader and bloom effects. creatures. Systems with vector-graphics displays pro- The much later Tempest 2000, released in vided developers with some capabilities that 1994, uses raster and vector idioms. In this ver- were not available a decade later. Thanks to sion, a tube’s rasterized wireframe, represent- the popularity of their vector games, Atari ing the landscape of a level, rotates before the developed a general computing system to

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aid in their creation. The Atari Analogue Vec- conversion between them is often necessary. tor Generator (AVG) is a special set of chips Theimportanceofthesetwohardwaredisplay used to run the graphics systems of Asteroids, systems continues to extend beyond the com- Battlezone, Tempest, Gravitar,andStar Wars. mercial life of random-scan CRTs and the pres- The AVG, which went through several ver- ence of XY graphics games in arcades. sions, facilitated numerous useful operations for vector rendering. These included drawing Conclusion a vector from the current cursor position to a The random-scan display technology has new (x, y) position, positioning the cursor at faded, and even the once-ubiquitous raster- the center of the screen, setting the color and scan CRTs are rapidly yielding to flat-scan dis- intensity for new vectors, and program flow plays. Nevertheless, these displays left their operations such as jumps and subroutines.2,5,11 traces directly and indirectly on many different Of course, Tempest 2000, Geometry Wars,and games, including some of the most influential other reimaginings of vector games were not home-console and arcade titles. And many of able to use such hardware. Those games the important concepts behind the two differ- required that new software subsystems be ent systems live on today in software. created to simulate the vector effect in raster- Today’s modern techniques for 3D graph- or polygon-based graphics systems. ics descend partly from early vector wireframe Vector art has persisted and evolved in techniques. XY graphics display hardware is computer graphics in other ways as well. certainly not in widespread use, but XY Just as vector shapes allowed game develop- (and XYZ) ways of thinking have become ers to enact translations and scaling effects prevalent because of changing graphics with ease, other forms of computer art bene- capabilities and because of software systems fited from mathematical representation. Vec- such as Flash. tor displays have allowed higher-resolution Consideration of the two display systems is graphics than would have been possible at no doubt important for understanding the his- the time of Asteroids. tory of videogames. The way in which the dif- Bandwidth became a limitation in later ferent technologies supported and constrained eras. On the early Web, slow dial-up connec- game development sheds light on contempo- tions conflicted with users’ increasing expec- rary and past development practices and how tation for rich graphics and animations, a they relate to computer hardware. Beyond trend begun by GUI operating systems and that, the healthy competition between ran- multimedia CD-ROMs. Here vector graphics dom and raster, and the interesting challenges offered a solution as well. Because vector art that prompted developers to innovate when is drawn based on a few parameters rather moving between the two systems, suggest than being rendered as pixmaps, a PC can eas- that standardization is not always ideal. A ily be made to draw many frames of an anima- monoculture of videogame displays (or other tion from instructions rather than data. These hardware) might be convenient, but working sets of instructions take up less memory and on and across different technologies can pro- require that less data be sent over the network. voke new, striking developments. Such a factor was primary in the design of FutureSplash Animator (1996), the program Acknowledgments that became Macromedia Flash and then Adobe Flash. Macromedia’s other popular an- The text of this article from ‘‘The building imation product, Director, had been designed blocks of Star Castle’’ through ‘‘Serving up Yars’ Revenge for use as CD-ROM and desktop software and ’’ has been adapted from chapter uses raster graphics primarily to present pho- five of our book Racing the Beam (MIT Press, torealistic effects. Thanks to the widespread 2009). This book is the first in the Platform Stud- adoption of broadband Internet service, bit- ies book series (http://www.platformstudies. map art is more frequently used in Flash com) the authors are coediting at the MIT Press. compositions because it can be rendered fairly efficiently on today’s computers. The References and Notes distinction between raster- and vector-based 1. J.D. Foley et al., Computer Graphics: Principles representation is one that continues to affect and Practice, Addison-Wesley: 1996. not only what we see on the Web, but also 2. It’s at least amusing to note that Computer how geographical data is abstracted in geo- Space, the first arcade game, was a raster graphic information systems (GISs), where a adaptation of a game that ran on a Type 30 debate between the two styles is ongoing and Precision CRT display, a random-scan display.

42 IEEE Annals of the History of Computing Pong was originally developed for the TV. Nick Montfort is an associ- Although there are probably more compelling ate professor of digital media reasons for Pong’s commercial success, which at the Massachusetts Institute greatly outstripped that of Computer Space, of Technology. He collabo- these two games do provide examples of one ratesonliteraryprojectsand unsuccessful ‘‘port’’ from one display technol- writes poems, text generators, ogy to another and one successful game that and interactive fiction such was done with a specific display in mind. as Book and Volume and Ad 3. S. Stilphen, ‘‘Interview with Howard Scott Verbum. Montfort has a PhD in computer and in- Warshaw,’’ Apr. 2005; http://www.digitpress. formation science from the University of Pennsyl- com/archives/interview_warshaw.htm. vania. Contact him at [email protected]. 4. H.S. Warshaw, interview by J. Weesner, Apr. 2007. 5. T. Skelley, ‘‘Tim Skelley’s History of Cinema- Ian Bogost is a videogame tronics,’’ June 1999; http://www.dadgum.com/ designer, critic, and researcher giantlist/archive/cinematronics.html. as well as an associate profes- 6. J. Novak, Game Development Essentials: An sor at the Georgia Institute Introduction, Thompson Delmar, 2004. of Technology and founding 7. Z. Whalen, ‘‘Lost in Emulation: World of Differ- partner at Persuasive Games. ence in Videogame Typography,’’ Proc. 3rd Ann. His research considers video- UF Game Studies Conf., 2007. games as an expressive me- 8. D. Debro, ‘‘YarsRevenge.asm,’’ Disassembly of dium, and his creative practice focuses on games Yars’ Revenge with labels and comments added, about social and political issues. Bogost has a 21 Sept. 2005. PhD in comparative literature from the Univer- 9. Although the 2D combat tank games corre- sity of California, Los Angeles. Contact him at sponded to the 3D, first-person Battlezone, [email protected]. Rotberg’s other game, Red Baron, can be seen as a 3D version of the combat biplane games. 10. D. Kushner, Masters of Doom, Random House, 2003. For further information on this or any other 11. See also http://www.coinop.org/kb_dl.aspx/KB/ computing topic, please visit our Digital Library gametech/atari_xy.html, 2007. at http://computer.org/csdl.

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