note: on the internet I found existing tools for using an rtlsdr and things like an arduino as logic analysers.
with a chip to multiplex things I could possibly breadboard a small system that would plot the behavior of every bus line from a system by toggling its power and walking the chip.
the first logic analyser project I found was "sigrok":
sigrok.org
the gui might then be done with some kind of sigrok tool.
[the feedback steps between logging and the gui might be too slow to upsample the input using phase information. there may be a pair of tools that are hackable together though.]
[it's a little sad to use rtlsdr without improving tooling around existing frameworks, but we do badly need logic log]