because SimdShape works out that its maximum scalar size is
11, and sets Shape.width to 11 when SimdScope is set in
scalar mode. When scalar=False, full SIMD is activated and
-the resultant HDL combines vec_el_counts with expshape to create
-1xFP64, 2xFP32, 4xFP16, 4xBF16 where the exponents are 11, 8, 5, 8
+the resultant HDL combines vec_el_counts with expshape as part
+of an ALU with inputs that can be
+1xFP64, 2xFP32, 4xFP16, 4xBF16, where the exponents are 1x11, 2x8, 4x5, 4x8
respectively.
Behind the scenes, when calling SimdShape.Signal in SIMD mode,