Changes

* VRAM read/write via registers, 0,1,2 and 3,4,5 and port 0 use *logical* addresses and not physical addresses. Writing in one mode, and then reading back in another can yield different data because the addresses are translated from physical to logical based on the mode.

* Testing indicates TP operates on the data that will be written (SC) and happens *before* write mask. DC is read from physical VRAM. WC is the result of LOP on SC and DC and is the data that will be written. WC is the data that is masked using the write mask.