HDMA
The Super Nintendo's way of writing fresh values into the video registers between every scanline, without the CPU lifting a finger.
H-blank DMA has eight channels. Each one is given a table in memory and a register to target, and during the brief pause at the end of every line it feeds in the next value. Scaling, scroll position, palette entries or window edges can therefore change line by line while the CPU gets on with the game logic.
It is behind most of what makes SNES graphics recognisable: the perspective in Mode 7, where the matrix is recomputed per line so the plane tilts towards the horizon, skies with smooth colour gradients, wobbly water reflections and spotlight windows. The idea is the same as the Amiga's Copper or the raster interrupts of C64 demos, but table-driven — no code runs, it is just data streaming in at the right moment.