Yes, analogue computing. It's a world of pain though, each individual operator in each individual device is going to have a slightly different level of accuracy

Yes, analogue computing. It's a world of pain though, each individual operator in each individual device is going to have a slightly different level of accuracy, which is also going to be affected by temperature, so you need to learn a whole new set of analytical skills and operational practices to ensure that your model works correctly on each one at a customer location. And that's not even thinking about the testability at shipment of the devices being in spec, and that they are at all operating temperatures and over the lifetime of the device.