Racing the Beam : the Atari Video Computer System - Index of

merely press the joystick in a compass direction to go to the next screen.
Rather, the player moves a square around on that screen, perhaps choosing
to continue to the edge so that the square moves off the current screen
and onto the next screen.
This movement set the standard for later action-adventure games,
including the tile-based games in the Ultima and The Legend of Zelda series.
Even though most contemporary action-adventure games use threedimensional
(3D) rendered worlds rather than two-dimensional (2D)
top-down ones, the concept of movement from room to room, as in a
castle or dungeon, persists. Robinett’s solution to contiguous movement
through space may seem obvious to us now, but it required a great deal of
engineering, given the nature of VCS screen graphics. The Adventure manual’s
quaint explanation of screen-to-screen movement testifi es to how
novel and unusual the scheme was at the time: “Each area shown on your
television screen will have one or more barriers or walls, through which
you CANNOT pass. There are one or more openings. To move from one area
to an adjacent area, move ‘off ’ the television screen through one of the
openings; the adjacent area will be shown on your television screen.”
More than any other feature of the machine, the register-based method
of drawing the screen a line at a time as discussed in the previous chapter
made some styles of play and forms of game harder than others to implement.
Consider Warren Robinett’s explanation of his early work on
Adventure development: “A month later, I had a prototype: the player
could move a small square “cursor” from screen to screen, picking up the
little colored shapes to be found on some of the screens, which were connected
edge to edge. And there was a pesky dragon that chased the cursor
around, trying to eat it. Exhausted, I went on vacation.” 5 Robinett actually
left the intense work environment of Atari at that point for a monthlong
vacation. 6 What was so taxing about programming the Atari VCS?
How would a person need a month to recover from this sort of work?
Programming was, after all, Robinett’s job, and a VCS cartridge usually
took about six months to complete. What he accomplished at this early
stage probably sounds rudimentary to modern-day programmers and to
today’s players.
But adapting the system to allow for a large virtual space was not
simple at all. To move from screen to screen, the program must track the
location of the “cursor” and determine whether this location has passed
beyond one of the edges of the screen. Then, the program must redraw the
new screen and position the cursor at the opposite end.
This operation is complex, because the VCS display is not divided into
pixels as a modern raster display is. Instead, the screen is built out of units
3 Adventure [49]