The DOS partition limitation is derived from the File Allocation Table (FAT). DOS uses the FAT to keep track of file addresses. The DOS FAT 16 is only capable of working with 32,768 bytes per cluster and no more than 65,536 clusters. If you multiply the two numbers together, you get the maximum partition size that DOS can use (2,147,483,648 bytes or 2048 MB {2,147,483,648 / 1024 2}).