PC DOS 1.1

IBM PC DOS is a DOS system for the IBM Personal Computer and compatibles, manufactured and sold by IBM from the 1980s to the 2000s.

In September of 1981 IBM release an updated verion of it's PC DOS 1.0. The new version 1.1 added support for 320 kB double-sided floppy disk.

PC DOS 1.1 followed by PC DOS 2.0 in March of 1983.