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.
Released in December of 1985 PC DOS 3.2 required
128 kB RAM and added 3.5-inch FDD support. OS
was supplid on one 720 kB 3.5-inch floppy disk
or two 5.25-inch 380 kb disks.
In April 1987 IBM released an updated verion PC