  We present a compact and transportable inertial sensor for precision sensing
of rotations and accelerations. The sensor consists of a dual Mach-Zehnder-type
atom interferometer operated with laser-cooled $^{87}$Rb. Raman processes are
employed to coherently manipulate the matter waves. We describe and
characterize the experimental apparatus. A method for passing from a compact
geometry to an extended interferometer with three independent atom-light
interaction zones is proposed and investigated. The extended geometry will
enhance the sensitivity by more than two orders of magnitude which is necessary
to achieve sensitivities better than $10^{-8} $rad/s/$\sqrt{\rm Hz}$.
