ATM was an interesting networking tech. I like how it was a hybrid of packet and circuit switching where you could dial another machine to setup a call (this is Telephone tech after all) and you were handed a an in-order point-to-point byte pipe. Made TCP unnecessary. Unfortunately Ethernet was eating its lunch in the 90's leaving it to die a slow death in Telephony.

A similar tech was the old Bell Labs Datakit, https://en.wikipedia.org/wiki/Datakit which was supported in early versions of Plan 9, http://man.postnix.pw/plan_9_2e/3/datakit. The Datakit device and dk conversation services enabled you to dial a machine and you'd get a stream which is basically an fd you just read/write. They could use this to dial a disk server using 9p over dk to boot a terminal using datakit. Since 9p multiplexes access to files and files can provide services you could then import an IP stack running on a remote machine to get IP over 9p over datakit.

Another thing I find highly ironic is how they duck tape TSN and other QoS stuff on top of Ethernet to make it behave deterministically like ATM, the technology it destroyed.