Issue with the CADR (and Lambda ..) microcode isn't that it is hard to modify, it is that there is a very deep snake pit, and lots of complex interaction betwee

Issue with the CADR (and Lambda ..) microcode isn't that it is hard to modify, it is that there is a very deep snake pit, and lots of complex interaction between the microcode and the Lisp Machine. The CADR already had support for (pre-)Ethernet via microcode very early (~1979) and did it more or less the same way as for Chaosnet. The Lambda I think modified this quite heavily though to something else ...