Scrambling means that the logical structure, as seen by the user from
the outside of the chip, differs from the physical or topological
internal structure of the chip. The consequence is that
logically adjacent addresses may not be physically adjacent
(this is called address scrambling) and that logically adjacent
data bits are not physically adjacent (this is called data
scrambling).
The way address sequences and data patterns
appear on the outside of a memory may differ from their internal
appearance; this effect is referred to as scrambling.
Following paper is good -
https://ieeexplore.ieee.org/iel5/7805/21449/00994601.pdf?arnumber=994601