Original DIX Ethernet was standardized by my manager, David Redell of Xerox. It was the bare minimum to do the job, 6-byte station destination, 6-byte source address, 2-byte packet length, a 2-byte Ethertype field (the latter 2 were combined for networks with hardware framing), and 32-bit CRC. NO arc in the hardware. It leveraged the move to byte-based memories and small CPUs. It followed the end-to-end principle in system design just about optimally - the most minimal MAC design of all time. EASY TO BUILD UPON AND ENHANCE.

Ethernet (CSMA/CD) is a protocol that copies human speech patterns. After someone stops speaking people hear the quiet (carrier sense multiple access / CSMA) and wait a very short and randomized amount of time and begin to speak. If two speakers collide they hear the collision and shut up (CD - collision detection). They both pick a randomized amount of time to pause before trying again. On the second third etc. collision people wait longer and longer before retrying.

The thing about original ethernet (1981) is that it wastes 2/3 of the channel because a highly loaded channel has too many collisions and too many back offs. But deployment and wiring were expensive so running a single wire throughout a building was the cheapest possible way to start (enhanced by thinwire Ethernet and twisted pair to have a less bulky cable a few years later). The frame design was PERFECT and within ~10 years people were using ethernet frames to build switched networks and today only radio networks are CSMA/CD = Ethernet.