I tried the example that you gave, but the asm51 compiler says that there are two errors:

    1:	  0000	74 F4		mov a,#0F4h
    2:	  0002	78 04		MOV R0,#004h
    3:	  0004	78 00 00	CJNE A,R0,NOT_EQ
				       ^
			  @@@@@ illegal operand @@@@@

    4:				; ... .... ; R7 = 60H.
    5:	  0007	40 00		NOT_EQ: JC REQ_LOW ; IF A < R0.
					   ^
			  @@@@@ symbol not defined @@@@@

    6:				; ... .... ; R7 > 60H.
    7:				end