What every line do ?

For instance clr.w R4 this clear two bytes of the R4 henece the value is oxooo.

In your newly created file, add this source code . data .word 0x1234, 0x5678 .word 0xABCD Mem: .space 10 .text clr.w R4 mov.w X, R4 mov.b , R5 mov.w #16,R6 ; put your comments here for every line mov.w 2 (R7), R8 mov.w @R7, R9 mov.w #600,R10 mov.b #-3,R11 mov . w #-1,R12 add.w #4,R12 mov.w R12, Mem jmp $ ; infinite loop to end program