DOS is a family of disk operating systems primarily consisting of MS-DOS and a rebranded version under the name IBM PC DOS which were introduced in 1981, as well as some later compatible systems from other manufacturers: DR-DOS (1988), ROM-DOS (1989), PTS-DOS (1993), and FreeDOS (1998). MS-DOS dominated the x86-based IBM PC compatible market between 1981 and 1995. 

Dozens of other operating systems also use the acronym "DOS", including the mainframe DOS/360 from 1966. Others are Apple DOS, Apple ProDOS, Atari DOS, Commodore DOS, TRSDOS, and AmigaDOS. 

IBM PC DOS (and the separately sold MS-DOS) and its predecessor, 86-DOS, resembled Digital Research's CP/M—the dominant disk operating system for 8-bit Intel 8080 and Zilog Z80 based microcomputers. DOS instead ran on Intel 8086 16-bit processors. Starting with MS-DOS 1.28 and PC DOS 2.0 the operating system incorporated various features inspired by Xenix, Microsoft's variant of Unix. 

When IBM introduced the IBM PC, built with the Intel 8088 microprocessor, they needed an operating system. Seeking an 8088-compatible build of CP/M, IBM initially approached Microsoft CEO Bill Gates (possibly believing that Microsoft owned CP/M due to the Microsoft Z-80 SoftCard, which allowed CP/M to run on an Apple II). IBM was sent to Digital Research, and a meeting was set up. However, the initial negotiations for the use of CP/M broke down; Digital Research wished to sell CP/M on a royalty basis, while IBM sought a single license, and to change the name to "PC DOS". Digital Research founder Gary Kildall refused, and IBM withdrew. QUESTIONS:

Q1:
1. What kind of processors did IBM use in their PC's?
2. IBM used what kind of processors in their PC's?
3. 
Q2:
1. What is the name of the person that IBM initially approached?
2. Which person was initially approached by IBM?
3. 
Q3:
1. What reason did IBM have for approaching Bill Gates?
2. Why did IBM initially approach Bill Gates?
3. 
Q4:
1. What card may have given IBM the impression that Microsoft owned CP/M?
2. IBM may have gotten the idea the Microsoft owned CP/M thanks to what card?
3. 
Q5:
1. What did the Microsoft Z-80 SoftCard do?
2. What could be done thanks to the Microsoft Z-80 SoftCard?
3. 
Q6:
1. What does the acronym DOS stand for?
2. What is the full meaning of the term DOS?
3. 
Q7:
1. What are the two main versions of DOS that were introduced in 1981?
2. In 1981, which two main versions of DOS were introduced?
3. 
Q8:
1. In what year were MS-DOS and IBM PC DOS introduced?
2. MS-DOS and IBM PC DOS were introduced into the market in what year?
3. 
Q9:
1. What type of market was dominated by MD-DOS in between 1981 and 1995?
2. In between 1981 and 1995, what type of market was dominated by MD-DOS?
3. 
Q10:
1. During what years did MD-DOS dominate the x86-based IBM PC compatible market?
2. The x86-based IBM PC compatible market was dominated by MD-DOS between what years?
3. 
Q11:
1. FreeDOS was launched in what year?
2. What was the year when FreeDOS was launched?
3. 
Q12:
1. What is the name of the system that was launched in 1988?
2. In 1988, which system was launched?
3. 
Q13:
1. Dozens of operating systems use the acronym "DOS" including what mainframe as of 1966?
2. As of 1966, what mainframe uses the acronym "DOS" on top of dozens of other operating systems?
3. 
Q14:
1. What is the total number of Apple versions that use the acronym "DOS" that are mentioned in the article?
2. The articled mentions how many Apple versions that use the acronym "DOS"?
3. 
Q15:
1. What is one of the Apple versions that uses the acronym "DOS" that is mentioned in the article other that Apple DOS?
2. Other than Apple DOS, what version of Apple is mentioned in the article that uses the acronym "DOS"?
3. 
