MESA Electronics’ 4I69 is a general-purpose programmable I/O card for the PC/104-PCI bus. The card uses an XC6SLX16 or XC6SLX25 Xilinx Spartan6 field-programmable gate array (FPGA) for all logic. The FPGA configuration is downloadable from the PCI bus side, allowing creation of almost any kind of specialized I/O function. A bus mastering PCI bridge enables the card to work with both 5-V and 3.3-V PCI buses and support high FPGA/PCI bus transfer rates. It uses three 50-pin connectors with I/O module rack-compatible pin-outs and interleaved grounds. A 50-MHz crystal oscillator provides a reference clock that can be multiplied by the FPGA’s delay-locked loops for higher clock speeds.