Hunting a 34 year old pointer bug in EtherSlip

Today, the same is true of many other physical-layer protocols that developed later, such as WiFi and the GSMA mobile standards; they seem to have converged on the Ethernet frame format at the software interface, presenting the appearance of an Ethernet NIC to software, because that's the easiest way to make use of existing network stacks. There's also the weirdness of tunneling protocols like PPPoE which only exist to tunnel Ethernet through non-Ethernet systems.