Although it's hard to argue about what a theoretical unfree society would have accomplished, we know the USSR had the M-40 system in the early 1950s. That was

Although it's hard to argue about what a theoretical unfree society would have accomplished, we know the USSR had the M-40 system in the early 1950s. That was a full duplex radio data network for missile defence. Whether that would have morphed into the civilian Internet in the same way ARPANET did is impossible to say. Which basic technology - other than the telescope - was missing from the Roman's knowledge that would have enabled a proto-Inernet?