 EvStack was a pretty much complete redesign of the input and output subsystem that allowed for events (thus the "Ev") to flow through a "Stack" of modules that can be configured to manipulate them.EvStack is a very powerful concept, allowing e.g.to have two keyboards attached to the same machine, one operating a text console on one graphics adapter and one operating a graphics console on the other (as was demonstrated on the Linux-Kongreß ´97) and even allows for having different keyboard layouts on different virtual consoles or attaching keyboards via network.