A framebuffer is an area of memory in a computer system (remember, arcade games and consoles are mostly computers, too!) which is shared between the CPU and the video circuitry. Therefore, when the CPU writes to this area, changes appear on the screen. The actual arrangement of framebuffers varies wildly across designs; in black and white systems like Space Invaders or the original Macintosh each bit represents one pixel on the screen and therefore a single 8-bit byte controls 8 pixels on the screen.
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