Tyre Pressure Gauge Main IC

This is the main chip from a tyre pressure gauge. It's an AMI, but I can't see any part number on there. It's made in Idaho though, if you look carefully.

I'm not sure if this is a microcontroller. I'm tending towards not, as there doesn't seem to be any ROM or RAM, at least not in quantity. It looks to me like this is discrete logic, in the top half, with some registers and so on dotted about.