Yes, that's what I was thinking.

That's why I was suggesting the use of that FTDI DLP245UM USB-FIFO adapter. It comes with a pretty simple-to-use driver and looks, at the target end just about like a FIFO, since that's what it is. It only operates at 10 MBytes/sec, but even if you sample at 200 MHz, transfers at 10 MB are pretty adequate.

For small buffers, a serial link would work, too, I guess. The advantage of the USB/FIFO device is that it is bidirectional and has a sufficient signal set to allow attachment of primitive hardware to allow one to fill/empty the FIFO with a minimum of hassle and without adding intelligence beyond what a few registers, gates, and flipflops can do. I've had a project in my bottom drawer for a while that does a 16-signals, 2 clocks, 2 qualifiers, sampler in an XC2S200 with one of these, not that an FPGA of that size is necessary, but because it's conveniently located on a board that will accomodate the rest of the stuff. I'll get back to it one of these days. I've already got the cable, (swiped it from an old ICE, actually) and the rest will be pretty easy, since that cable fits the "grabber clips" I already have from my Tek portable.

RE