PC-DOS 320K format

The PC-DOS 320K format was one of several low-capacity 5 1/4" disk formats used on IBM PCs and compatibles in the early days of PC-DOS before the PC-DOS 360K format became the standard. It used a double-sided, double-density disk with 40 tracks per side with 8 sectors per track, and 512 bytes per sector. Data was stored with MFM encoding. The disk turned at 300 RPM. These disks were generally used with FAT12 file systems under the MS-DOS or PC-DOS operating system.

This format was the double-sided counterpart of the PC-DOS 160K format, but was soon superseded by the 360K format made possible by expanding the number of sectors per track to 9.

Links

 * Info on MS-DOS 1.x - 2.x disk formats
 * Early PC-DOS source code