Explain why both the HALT operation code described in Figure 6.5 and the .END pseudo-op mentioned at the end of this section are needed in an assembly language program and what might happen if one or both were omitted.

FIGURE 6.5 FIGURE 6.13 Binary Op Code Operation LOAD X STORE X CLEARX ADD X INCREMENT X SUBTRACT X DECREMENT X COMPAREX Instruction Format: Op Code 4 bits Address 12 bits Meaning R ? CON(X) 0-CONX Object Program: 0010 Machine Language Instruction 1101 000000001001 1101 000000001010 0000 000000001001 0111 000000001010 1001 000000000111 1110 000000001001 1000 1110 000000001010 ess Meaning 0100 0101 0110 0111 CON(X) + 1 ? CON(X) 0010 LOAD X COMPARE Y JUMPGT DONE OUTX JUMP LOOP OUT Y CON(X)-1-CONCX) if CONCX)> R then GT 1 else 0 if CON(X) = R then EQ = 1 else? if CON(X)