  We demonstrate lasing into counter-propagating modes of a ring cavity using a
gas of cold atoms as a gain medium. The laser operates under the usual
conditions of magneto-optical trapping with no additional fields. We
characterize the threshold behavior of the laser and measure the second-order
optical coherence. The laser emission exhibits directional bistability,
switching randomly between clockwise and counter-clockwise modes, and a
tuneable nonreciprocity is observed as the atoms are displaced along the cavity
axis.
