Safe operating systems mandated for railway applications can take advantage of MEN Micro’s SIL 4-certified, redundant CompactPCI PlusIO single-board computer (SBC). With both fail-safe and fail-silent architectures, the COTS-based F75P SBC helps ensure safe computing during normal operation, as well as when potential failures or faulty data are present. In fail-safe operations, the system shuts down completely upon detection of an error. For fail-safe operations, it will still run, but not transmit incorrect data. Two independent Intel processors offer redundant control, running the safe QNX board support package with supervisory units to monitor environmental factors. The third Intel processor, implemented at the top-most protocol layer (“black channel”), controls the I/O without interfacing with any safety protocols. This creates reliable transmission of commands from two control CPUs to the interfaces across an internal FPGA-based Ethernet link. All Intel processors are based on the Atom E6xx family, and operate up to 1.6 GHz. Each control CPU offers 512 Mbytes of DDR2 RAM, while the I/O processor features 1 Gbyte of DDR2 plus 8 kbits of nonvolatile FRAM. Front I/O on the third processor includes VGA, two fast Ethernet, and two USB. The rear includes one PCI Express and one SATA port, plus four USB and two Fast Ethernet interfaces.