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The 8085 has certain address locations it goes to under certain hardware conditions.? (without me looking them up, it's in the data sheet), there's one for power on reset, the hardware traps (rst 7.5, etc), interrupts and so on.

If you monitor the address lines on the processor (fortunately, 16 of them), then (for example) when the reset line goes active, the processor should show that the address lines go to zero (IIRC) and start to execute there.? In the 8085, you don't have vectors (the processor doesn't fetch and address from location 0, then use that to show where to execute (as in the 6800 or the 6500 series), but starts executing at that location.? Thus, the location typically contains a jump instruction which goes to actual code.

once you see that the location is being jumped to, you may be able to use the higher bit of the address to monitor the triggering event if you wish.

For an 8 bit microprocessor, a 32 bit is more of a minimum requirement, with 16 address, 8 data, and 8 other signals (ALE, R/W, etc).

Still, you could take the highest 4 bits of the address, run them through a 74LS20, then again to invert the answer, and that would give you some indication of the address if you start to trace further.

Harvey