MSX-DOS
Everybody has heard of MS-DOS, but Microsoft’s backport to 8-bit systems is more obscure.Since MS-DOS was practically a CP/M clone for 16-bit computers, Microsoft realized they could port it to 8-bit and it would be a binary-compatible cleanroom CP/M clone. And that’s what they did. It was sold as a standard for Japanese home computers — MSX, a predecessor of Xbox in both nomenclature and target market.The person tasked with creating this 8-bit port was Tim Paterson, the original creator of MS-DOS. Usually the story of IBM PC and Microsoft paints Paterson as a victim of Gates’s licensing machinations, but this MSX-DOS episode shows he continued to have a profitable relationship with Microsoft:’On 10 August 1983, Paul Allen called Tim Paterson, original author of 86-DOS and MS-DOS 1.x, asking him to do a "Z80 version of MS-DOS" for the MSX standard. At the time, Paterson was busy trying to get the first product of his startup Falcon Systems ready to go, so he suggested a few other developers, but Allen said he had already asked. Allen was in a hurry to get it done and nobody else could meet his timeline. Allen and Paterson finally agreed, and on 17 August, they signed an agreement to do "Z80 MS-DOS 1.25" for US$100,000 and the rights for Paterson's company to distribute MS-DOS 2.0, 2.5, and 3.0 with a hardware product without royalty.’