While not null

The idea is to keep "advancing" the pointer $s0 from node to node until it contains a null. This is done in a loop. The null pointer is detected with a beqz instruction.

main:
          la     $s0,elmnt01    # get a pointer to the first node
          
loop:     beqz   $s0,done       # while the pointer is not null
          lw     $a0,0($s0)     #   get the data of this node

          . . .                 #   do something with the node

          lw     $s0,4($s0)     #   get the pointer to the next node
          b      loop
          
done:    

Here is a picture that shows the pointer advancing through the nodes until it becomes null: