I've got some basic block structures in place.
These are the local maps, loaded as needed.
The user see a portion of the block.
The possiblity may occur where the user sees 4 different blocks at once on the screen.
Therefore I may pull sub rectangles from each block to create the entire user view.

This is done now and hopefully working. It proved rather challenging.
using modulus with blocks indexing from zero, confused me for a while but its not too bad now.
The next stage is getting a bit of movement.
Currently I'm not concerning myself with pixel by pixel movement but I believe I'll do it by writing outside the rectangle and allowing it to clip it.

First block by block movement. I don't know if I'll do any more tonight.
Still on the mouse chapter of my windows book, though quite near the end. The chapters are mammoth and there are nearly 20 of them :(