Just opened up one of my IAM’s to see what’s inside (I was hopefully it might have an ATMEGA like the bridge/netsmart) but no such luck:

The chip in the bottom right I think is a CS7760: http://www.chipsea.com/doce/product-detail-93.html (used to convert energy to pulses?)

Then on the reverse of the PCB the PIC16F689- so it doesn’t look like I’ll be doing anything much with it in a hurry!