I had thought that the difference between these meters was the ROMs and the zener diode, so when I opened a recently acquired 7071 I was surprised to find it fitted with ROMS quite clearly labelled 7081 5201 DC through 7081 5205 DC on the earthy board, and 7081 5251BA on the floating logic board. Now I'm wondering if there is just a solder jumper or coding resistor or similar on one of the floating boards that tells the processor(s) which type of meter it is. Does anyone know? Cheers David Partridge