Yes it is possible to add additional system memory to the CSPPC local PCI slot. The GREX when connected to the CSPPC adds GFX card memory (like a Voodoo), however it does not provide the software feature like Mediator does to add it as system RAM. So two problems with this as there is a missing software feature to remap PCI memory (really Zorro memory) into system memory and you need a GREX busboard.
Since the PCI connector on the CSPPC is undocumented it is unlikely someone is going to reverse engineer and design a Radeon adapter for the CSPPC.
