Why a crowded game screen made objects blink
Many older consoles drew the picture line by line, as the screen’s electron beam or display circuitry moved from top to bottom. Dedicated hardware units called sprites supplied movable images—such as a player, an enemy, or a projectile—but the hardware could handle only a limited number of sprites on any one horizontal line. A screen might have room for many objects overall and still run out of capacity where several crossed the same row.
When too many sprites competed for that row, some could disappear. The limit was in the hardware’s ability to fetch and draw their image data in time, not in how many characters the game’s designers wanted to show.
Taking turns, one frame at a time
A common workaround was to divide the crowded objects into groups and draw one group on one frame, then the other group on the next. Because the display refreshed many times each second, each object appeared repeatedly rather than vanishing for a long stretch. The eye could blend those quick appearances into a rough impression of several objects being present together.
The trick traded a hard limit for a visible cost: flicker. The more groups a game rotated through, the less often each group appeared, making the blinking more noticeable. Some games also changed which objects got drawn first, so the same character would not always be the one that disappeared when the screen became busy.
In a crowded scene, that flicker was a clue to the machine’s underlying rhythm: the game was taking turns using a small number of drawing slots to keep more action on screen.
