Take into consideration that most of modern logic analyzers (saleae, saleae clones, etc) are protocol analyzers and some don't even have external clock input for state analysis. Zeroplus logic analyzers have external clock input. For serious parallel bus analysis, you need to get one of the vintage HP / Agilent / Tektronix logic analyzers like the Agilent 1670E, 1670G, 1680, etc. They offer a bunch of input ports including external clock, high sample rate, a lot of capture memory and some serious triggering capabilities.