LDC        RD, immediate-3                                                     ; "0" : - R D -   0 . . .
           RD, immediate-20                                                    ; "1" : - R D -   . . . .  ++ immediate

SHIFT+LDC  RD, immediate-3                                                     ; "0" : - R D -   1 . . .
           RD, immediate-20                                                    ; "1" : - R D -   . . . .  ++ immediate

                                                                               
