31 INT 31 - overwritten by CP/M jump instruction in INT 30
31 INT 31 - VIRUS - "Vacsina" series - INSTALLATION CHECK (NOT A VECTOR!)

 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E   
                                                
                      57                        
                                                
                                           EE   
                                              FF