Ah, sorry, I misunderstood your point. Anyway, this is getting a little far afield for TUHS, so at some point it would be better to move to the 'internet-history' list if you want to explore it in depth. But a few more... I assume you mean 'systems running TCP/IP'? If so, I really don't know, because for a while during that approximate period one saw many internets which weren't connected to the Internet. (Which is why the capitalization is important, the ill-educated morons at the AP, etc notwithstanding.) I have no good overall sense of that community, just anecdotal (plural is not 'data'). For the ones which _were_ connected to the Internet, then prior to the advent of the DNS, inspection of the host table file(s) would give a census. After that, I'm not sure - I seem to recall someone did some work on a census of Internet machines, but I forget who/were. If you meant 'systems in general' or 'systems with networking of some sort', alas I have even less of an idea! :-) Noel