+## Shift-and-add
+
+Shift-and-Add are proposed in [[ls004]]. They mitigate the need to
+add LD-ST-Shift instructions which are a high-priority aspect of both
+x86 and ARM. LD-ST-Shift is normally just the one instruction: Shift-and-add
+brings that down to two, where Power ISA presently requires three.
+Cryptography e.g. twofish also makes use of Integer double-and-add, so the value
+of these instructions is not limited to Effective Address computation.
+They will also have value in Audio DSP.
+
+Being a 10-bit XO it would be somewhat punitive to place these in EXT2xx when their
+whole purpose and value is to reduce binary size in Address offset computation,
+thus they are best placed in EXT0xx.
+
+