The MESA 7I90HD is a very low cost, general purpose, FPGA based programmable I/O card with a EPP parallel, RS-422 serial or SPI host interface. Dual FPGA configuration EEPROMs allow simple recovery from programming mistakes. Firmware modules are provided for hardware step generation, quadrature encoder counting,  PWM generation, digital I/O, Smart Serial remote I/O, BISS, SSI, SPI, UART interfaces and more.  All motion control firmware is open source and easily modified to support new functions or different mixes of functions. All I/O bits are 5V tolerant and can sink 24 mA. All I/O pins support 3.3V LVDS signaling. Socketed pullup resistors are provided for all pins so that they may be connected directly to opto-isolators, contacts etc.  The 7I90HD has 72 I/O bits available on three 50 pin connectors, all connectors use I/O module rack compatible pinouts and are compatible with all Mesa 50 pin FPGA daughtercards.