What feeds R100? Can you simulate weak and strong pullups with switches and resistors so I know what kind of voltage/current sources and sinks we're looking at? Are these pulses gozintas or gozoutas? Does everything run off of 5v?
I think an overall block diagram of what it is you are trying to do would be the best way to convey what your hoping to achieve. Something like CPU1}------{CPU2
I could not illustrate the point very well using ASCII but maybe you get my meaning?