lw          0       5       lots        loads register 5 with 10000
        lw          0       6       neg1        loads register 6 with -5
        lw          0       7       one         loads register 7 with 1
start   add         5       6       5           decrease register 5 by 5
iter    add         4       7       4           increments register 4 by 1
        beq         0       5       2           go to end of program when register5==0
        beq         0       0       start       next loop iteration
fin     halt                                    end of loop & program
lots    .fill       1000
neg1    .fill       -5
one     .fill       1