[__d]

In the early 1980s, an Ethernet adaptor required a lot of board space. They were often of similar complexity to the main CPU board. For example, this is DEC's first Unibus Ethernet: https://gunkies.org/w/images/1/16/DEUNA.jpg, which occupied two boards.

The software required to run a TCP/IP stack was also large, limiting the system to a handful of active sockets, and consuming large parts of the available CPU power to run something like Telnet or FTP.

It took a few years for CPUs to get more powerful, more RAM to become affordable, and for network hardware to become integrated onto the smaller boards like ISA or NuBus.