Title: "Designing the IEEE 802.12 transmission code."

Abstract: In 1995 the Institute of Electrical and Electronic Engineers (IEEE) approved the 802.12 international standard for transmitting information at 100Mbit/s over copper telephone cabling. Under this standard messages are encoded from 5-bit data groups into 6-bit code groups prior to transmission. The code mapping was chosen to satisfy physical economic and social constraints simultaneously.

Nine years after designing this code as a Hewlett-Packard employee and presenting its properties to the IEEE I have permission to explain its underlying structure. I shall show how the code was found using a combination of geometrical insight combinatorial reasoning and computer search.