In order to demonstrably satisfy hard real-time deadlines, a system mu
st be predictable, and in particular the kernel must be predictable. I
n this paper we present and analyse a predictable kernel related to AO
RTA, a formal design language for hard real-time systems. The features
of the kernel allow AORTA designs to be verifiably and semi-automatic
ally implemented, and enable verified guarantees to be given about the
real-time behaviour of the system.