And this is "a poor man's" overlay of the data buffer over the piece of the code, specified explicitly and manually at the time of writing the program (the "bigger" overlay mechanisms I know of are also specified at the time of writing the program, not at the time of build or link). As the "scratch" area was overlaid, nothing has to be loaded, that's the only difference to the typical overlay where more often some code would also be overwritten over some other code. The other difference to the "classical," "bigger" overlay is that this was done exactly once over the life of the program.