1998 Corolla Instrument Cluster Change Over

What is your question?

I just bought a 1998 Corolla without a tachometer. I've ordered a replacement instrument cluster w/ tachometer and have found it's a pretty quick change out. Toyota basically wired everything up but if the gage isn't included with the car package it just goes unused, so the connectors are the same. However, the milage for the digital display resides in the CPU in the instrument cluster. My question is does anyone know what the CPU chip looks like, and is it soldered in or inserted in a socket? I'd like to keep the real milage with the changeout and will need to transfer the CPU to the new instrument cluster.