They want you to overlook the fact that their JTAG-programmable PROMs are VERY costly. Some years back, a fellow at one of the major German universities published a "project" (that's what the XILINX software likes to call 'em) that used a CPLD to make an FPGA boot from a standard parallel flash device and also allowed you to program the parallel flash device from a serial port. Unfortunately, the version I have has insufficient documentation (perhaps because of my ignorance) to enable me to implement it. A JTAG-programmable 4Mbit flash ROM, e.g. XC18CV04 (?) was, when last I looked, was costing about $25US, in moderate (25-99) quantity, while a much larger (32Mbit) parallel flash PROM cost about $3. His CPLD, with the aid of an external jumper, would allow you to program the FLASH ROM from your serial port, then, with the jumper in the opposite setting, would enable you, then, to boot your FPGA from the FLASH ROM. This still strikes me as a very good approach, though I still wish I had the entire package so I could give it a try.

RE