1 Some of the implementation choices
2 ----------------------------------
6 Load from direct space:
18 1 is bad when x or y involve HL (1b)
20 1 = 12 + n*(8+8) - 8 20 36 68
21 1b = n*(12+12+8) 32 64 128
25 Hmm. (2) is too hard to support in the current model.