What is the history of MS Dos

MS-DOS originated from two operating systems, CP/M and QDOS. The program for CP/M (Control Program for Microcomputers) was created by Gary Kildal of Digital Research in the mid-1970s. And QDOS was created in 1980 by 'Tim Paterson' of 'Seattle Computer Products'. QDOS was largely based on CP/M. After this, in 1981 Microsoft bought QDOS from 'Seattle Computer Products' and gave it a new name 'MS-DOS 1.0'. Then after Microsoft made a lot of improvements in it, Microsoft gave it to IBM to use in their new personal computers.