So I was thinking of buying a logic analyzer and found that a lot of the cheap ones are good to only a few mhz, and the microcontroller based ones can't have big buffers. So I was wondering if I could just use ram as a buffer? Like if it has 16 data lines, a 20 bit address, could I just feed 16 digital inputs (the ram I'm looking at reads >2.2V as HIGH so should be compatible with 3.3V logiv), and a 20 bit address counter run by a very carefully picked out crystal or some other kind of stable clock generation? I figure if the ram has a 45 ns write time, I should be able to easily get 22 odd MHz for only a few bucks, and then read it back with a slow micro controller or something, it doesn't need to access that data very fast.
However, I find that usually when I (and many other newbies) have these "why doesn't anyone do this?" ideas, there's usually a good reason.