It's well known the X11 is capable of displaying a program's graphics output remotely.
I checked the source code of the earliest version of X I found (X10R3, from 1986), and I found that this version was also capable of doing this (I checked
XOpenDisplay(), and it uses BSD sockets, so it must have supported remote displaying).
I wonder, was X1 (from 1984) capable of doing the same? Or is there an even earlier system, which was capable of doing this?