An experimental optical memory system is described for evaluating the optical memory characteristics of MnBi films. The preparation procedure for obtaining large uniform films is discussed. These films require about 10 mW of laser power to write 1-μm bits and a coincident field of 600 Oe to erase them. A packing density of 1.5 × 108bit/in2with a typical signal-to-noise ratio of 10 is readily achieved. Large area films have been sample tested and found to be of usable quality over 99.9 percent of the area. Test bits have been repeatedly cycled to the Curie point more than 106times retaining an adequate signal-to-noise ratio.