In 1980, IBM launched an IBM PC new model, which adopts Intel 8086CPU, with 160KB disk drive and other input and output devices. In order to cooperate with this model, IBM needs a 16-bit operating system, and there is three mutual competitive systems: CP / M-86, P-System, and Microsoft's MS-DOS. Finally, Microsoft's MS-DOS has achieved war's victory and became an IBM new model operating system. In 1981, Microsoft spent the MS-DOS 1.0 and IBM PC prepared for half a year at the same time in the IT interface. The MS-DOS at the time was similar to CP / M similar to CP / M in order to adapt to IBM's plans and compatible with CP / M systems. But at that time the CP / M system was still the industry standard, MS-DOS compatibility was suspected.
