type of buffers / bus switches
(reported by Piotr Miedzik)
I haven't found any PMC carrier without 3.3V I/O support. I checked followed devices:
- PC motherboards have only 3.3v PCI slots
- VME CPU (including RIO)
- PCI-PMC carrier (depends on motherboard)
- PCIe-PMC carrier
- uTCA-PMC carrier
FPGA may have 3.3 volt banks with PCI compatible clamping diodes.
Maybe buffers are not necessarily anyway.
Buffers like SN74LVC8T245 should be considered anyway if someone will find 5V only pmc carrier.