In 1979 I designed and built prototypes of an early Local Area Network adapter I called the “Network Interface Box”, and explored forming a company to manufacture and sell them. The abstract of the proposal read:
“In the proposed network, limited programmable intelligence is located at every terminal to improve man-machine communication, effect packet mode operation, compensate for incompatibilities, and promote network evolution. In this paper, the authors design of a Network Interface Box (NIB) is determined from an analysis of the hardware alternatives in the categories of modulation, protocol, processor architecture, maintenance and cost, …. ”
Because LSI components implementing CSMA/CD protocols (Ethernet) did not yet exist, I designed an RS-422 based Manchester encoded HDLC framed variant of CSMA/CD that operated at 1Mbps using a standard Zilog SIO device. I remember having a lot of fun designing the phase locked loop clock recovery logic, and the miniature switching power supply. In homage to the movie”2001″, I decided to package it in a small 1x4x9 box (squares of the first three numbers) which was supposed to be stuck to the back of terminals with adhesive foam.
Although I made a network of four working prototypes, I never found the right team to join me in starting a company, and after talking with Bob Metcalfe at some of the early IEEE 802 meetings, felt it would be better to wait for Ethernet LSI to appear.
Here is a picture of a mockup and my hand drawn schematic.
Here is one of the four wire wrapped prototypes I made: