I must explain myself better. I have a program implemented by PLM51. I want to change the microcontroler in which the program run to a microcontroler P89C51RD2 of Philips, and I want to use the Boot ROM in my aplication that is implemented by PLM51. For using the Boot Rom I have to be able to call a rutine that has a specific address in the program memory. The address is 0FC00h.
I intended to do it implementing a module in assembler like this:

PUBLIC reprog
org 0FB00h

reprog:
ljmp 0FC00h

END

And in the PLM51 module I declared the rutine like this:

reprog: PROCEDURE EXTERNAL;
END;

And I called the rutine:
CALL reprog;

Do you have another solution?