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 1984 IBM adds support for IBM
Personal Computer/AT with the new PC DOS 3.0
operating system. Compared to the previos
version 2.1, the new version supports the AT's
DS/HD 1.2MB floppy disk drives. Also, the new OS
introduces FAT-16 file system on hard drives.
PC DOS 3.1 followed in March 1985.