The single operand instruction PUSH cannot use the internal constants (CG) 4 and 8. The other internal constants (0, 1, 2, -1) can be used. The Assembler version 1.08 and higher produces correct code. The number of clock cycles is different: PUSH #CG uses address mode 00, requiring 3 cycles, 1 word instruction PUSH #4/#8 uses address mode 11, requiring 5 cycles, 2 word instruction