Accent improves upon Aleph, fixing several problems and re-targeting hardware support for networks of workstation machines (specifically, the Three Rivers PERQ) instead of minicomputers.
Development of Accent led directly to the introduction of Mach, used in NeXTSTEP, GNU Hurd, and modern Apple operating systems including Mac OS and iOS.
The idea was to write a number of servers that would control resources on the machine, passing data along until it reached an end user.
This turned out to have a number of problems, notably that copying memory on their Data General Eclipse was very expensive.
Instances of a program opening ports were handed back different IDs, stored in a mapping in the kernel.
In the early 1980s many felt that future gains in performance would be made by adding more CPUs to machines, something the Accent kernel was not really equipped to handle.