Hi I've always had in the back of my mind, the thought of building something to capture the raw flux-transitions. I still think the easiest way is to use the SPI port of a DSP, like the 2181 or similar. These processors are quite fast and can post process the raw data into something that can be transferred to the host processor in a more condensed and slower rate. To keep Ethan happy, he could even used one of the old modem cards made by Digicom and Cardinal that have 2115 and 2111 processors on them. A few hardware hacks and it could be a disk data processor. These two modems, called soft modems can have the entire software loaded For those that don't have one of these older boards, a 2181 development board might be the way to go. It makes sense to keep the back disk controls from something simple like the parallel port and just use the DSP for the read/write of data. The advantage of such a system is that the part count is minimal. The 2181 has all of its RAM inside. It can bootstrap parallel or serial to a host PC. It can sample really fast. For those that really need it, it can be programmed in "C" ( although the assembly is very clean ). The entire unit can be done in less than 10 IC's. There are distinct advantages to keeping the data processor separate from the host. One doesn't need to be concerned with how to handle other system level interrupts. One can buffer the data for safer transfer rates to the host system's mass storage. One thought, although the CatWeasel used sample rates on the order of 40MHz, adding a simple flopflop to the input significantly reduces the sampling rate needed( as I've stated before ). Dwight