What is the CPIOM in the IMA?
In the IMA architecture, processing modules are hosted in a cabinet and are interconnected via a high speed bus. B777 uses "SAFEBUS" which is ARINC 659 on the backplane and ARINC 629 externally (same protocol, different physical layer). Airbus uses ARINC 664 internally and externally for the bus. Legacy bus interfaces go through an I/O module or other bus conversion interface.   

The Airbus IMA contains 7 CPIOM (Core Processing &amp; I/O Modules) that support both processing capability and I/O interfaces on a single module. It also includes one I/O Module (IOM) connected to the ARINC 664 bus for additional I/O.  

The B777 AIMS cabinet contains Core Processing Modules (CPM) and separate I/O Modules (IOM).   

The same functions exist in both, it's just that the Airbus CPIOM is a single module where B777 has two modules for the equivalent functionality.  

And in a similar vein, the B787 IMA contains "GPMs" or General Processing Modules. It also contains two ARINC 664 network switches (network I/O for the cabinet). There are no direct legacy connections to the GPMs. Legacy (ARINC 429, CAN, discrete, analog) buses are connected to the external ARINC 664 network using Remote Data Concentrators (RDC).