Which of the following are 'legal'? ld OP1,a ld a,OP1 add OP1,26 dec OP1 ld OP2,HL ld HL,OP2 ld OP1,OP2 ld OP1,(score) ld (score),OP1 ld OP1,2 Please mark which ones work and which ones don't. And if they don't how can it work.