VPX / VME
Size: 3U and 6U
VME is a computer bus standard originally developed for the Motorola 68000 line of CPUs, but later widely used for many other applications and standardised by IEC as ANSI/IEEE 1014-1987. VMEbus is physically based on the Eurocard sizes, mechanicals and connectors, but uses its own pinout system, which Eurocard does not define. It was first developed in 1981 and continues to see widespread use today.
VPX (VITA 46) is the successor to VME for all harsh environment applications requiring high-speed I/O between FPGAs. Enormous backplane bandwidth potential thanks to the MultiGig connector.