This is the self-booting (via PC-DOS) Reference/Setup disk needed to configure the Tandy 5000 MCs NVRAM with MicroChannel card descriptions so the machine will boot. ┬áPrior to the Radio Shack corporate auction on July 10, 2017, this disk was unobtanium. ┬áDuring the auction, I purchase the corporate museum’s 5000 MC and the machine had the 1.02.03 reference disk sitting in the floppy drive! ┬áPlease pay appreciation forward and help keep these very unique machines alive and running forever! ┬áThe 5000 MC Reference Disk has a label that indicates the RS Catalog # is 25-6000.