Artesyn MVME51005E SBC Installation and Use (July 2014) - Manual (Page 127)

Programming the MVME5100
MVME51005E Single Board Computer Installation and Use (6806800A38D) 129
7.3.5.2.2 Role of the Universe ASIC
Because the PCI bus is little-endian while the VMEbus is big-endian, the Universe PCI/VME bus
bridge ASIC performs byte swapping in both directions (from PCI to VMEbus and from VMEbus
to PCI) to maintain address invariance, regardless of the mode of operation in the processor’s
domain.
7.3.5.3 VMEbus Domain
The VMEbus is inherently big-endian. All devices connected directly to the VMEbus must
operate in big-endian mode, regardless of the mode of operation in the processor’s domain.
In big-endian mode, byte-swapping is performed first by the Universe ASIC and then by the
PHB. The result is transparent to big-endian software (a desirable effect).
In little-endian mode, however, software must take the byte-swapping effect of the Universe
ASIC and the address reverse-rearranging effect of the PHB into account.
For further details on endian considerations, refer to the MVME5100-Series Single Board
Computer Programmer’s Reference Guide.