  We show that the bounded derived category of regular holonomic D-modules on a
smooth variety is equivalent to the homotopy catgory of compact (or
constructible) modules over the motivic ring spectrum $H_{dR}$ representing
algebraic de Rham cohomology. This equivalence is compatible with the six
functors on both sides. This way, the classical functors in the world of
D-modules, $f_! := D_Y f_* D_X, f^* := D_X f^! D_Y$ ($f: X \to Y$), are
conceptually explained and embedded into a larger and more flexible framework.
We also apply this equivalence to obtain a motivic t-structure on
$H_{dR}$-modules on not necessarily smooth schemes.
