A scratchpad is originally a pad of paper for preliminary notes or sketches or writings, etc.
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Scratchpad memory also known as scratchpad, scatchpad RAM or local store is a high-speed internal memory used for temporary storage of calculations, data, and other work in progress
Ageia's PhysX chip utilizes scratchpad RAM in a manner similar to the Cell; its theory states that a cache hierarchy is of less use than software managed physics and collision calculations.