MS-DOS, one of the most popular (but not the only) disk operating systems for IBM-PC computers, "born" in 1981 to be more precise in August, twelve. Although it was responsible for putting Microsoft on the map and make my youth even more interesting and fascinating and pimple-free. I still remember and i still have a working euro-pc, the original ms-dos diskettes and the oiginal manual of MS-DOS 1.0 and some of those very goods .pct 8bits files. 

The first version, PC-DOS 1.0, was released in August 1981. It supported up to 256 kB of RAM and two 160 kB 5.25" single-sided diskettes. May 1982, PC-DOS 1.1 introduced support for double-sided 320 kB floppy disks.