  We present a numerical analysis of an incompressible decaying
magnetohydrodynamic turbulence run on a grid of 1536^3 points. The Taylor
Reynolds number at the maximum of dissipation is ~1100, and the initial
condition is a superposition of large scale ABC flows and random noise at small
scales, with no uniform magnetic field. The initial kinetic and magnetic
energies are equal, with negligible correlation. The resulting energy spectrum
is a combination of two components, each moderately resolved. Isotropy obtains
in the large scales, with a spectral law compatible with the
Iroshnikov-Kraichnan theory stemming from the weakening of nonlinear
interactions due to Alfven waves; scaling of structure functions confirms the
non-Kolmogorovian nature of the flow in this range. At small scales, weak
turbulence emerges with a k_{\perp}^{-2} spectrum, the perpendicular direction
referring to the local quasi-uniform magnetic field.
