Perhaps there were other ways to see whether there was activity on the bus, but I was thinking of having a scope that was useful for the 8 MHz bus speed. Yes, they existed. On the other hand, they were not affordable for most people.

And yes, memory was expensive back then. I remember spending several hundred dollars to get 16 MB in 1992. That purchasing decision biases my computer purchases to this day. I still over provision RAM after reaping the benefits of it over 30 years ago.