The present invention provides an apparatus for programming functions of a display. The apparatus comprises a memory, a programming device, and a program code checking unit. The memory is for storing a program code. The programming device coupled to the memory is for reading the program code with a predetermined length from the memory. The program code with the predetermined length is part of the program code. The program code checking unit coupled to the programming device is for checking whether the program code with the predetermined length is consistent with a predetermined state, and for selectively generating a control signal. Under control of the control signal, the programming device determines whether to write the program code with the predetermined length into a memory of the display.