I've got a confession, I don't have an Arduino and have never programmed one but http://www.allaboutcircuits.com/projects/build-a-desktop-industrial-automation-trainer/ has caught my eye, as have many examples in here. This post uses an Arduino to sequence through a hard-coded output list, with each transition delayed by a second. Unless interrupts are involved, the controller is just stuck there during that second, doing nothing and responding to less. All this is a general...
Preventing delay() from blocking programs - Arduino.
Preventing delay() from blocking programs - Arduino.