Stage 1

• All the OBD software saved in ROM
• Program and data one unit
• Software changes with exchange of ROM
• New programming only by manufacturer

Stage 2

• Software saved in EPROM
• Program and/or data in preinstalled chip partial or all programmable
• ROM enhanced to EPROM
• Repair with exchange of EPROM

Stage 3

• Software saved in EEPROM
• Divided in fixed program section and flexible data section
• Chip programming on board of the car

Stage 4

• Software saved in EEPROM II
• Two Flash technic variants:
• 1. Fixed program section and changeable data section
• 2. Variants encoding with activation of several foreseen variants
• For 2. technic: later activation of fields possible

Stage 5

• Software saved in EEPROM
• Program section and data section are flexible
• With Flash technic all software only as one unit reflashable
• Field programming only as complete flashing possible
• Conflicts with safety systems possible