Thinking about it, The EFI on my '75 V12 XJ-S is analogue Lucas/Bosch D-Jetronic, but it doesn't (if I remember correctly) even have any op-amps. The entire ECU comprises about 25 small signal transistors plus the injector drivers. It must be said however, that one of the reasons I am here is to design a digital EFI to replace it. regards, Mike