MSX-DOS is a discontinued disk operating system developed by Microsoft's Japan subsidiary for the 8-bit home computer standard MSX, and is a cross between MS-DOS v1.25 and CP/M-80 v2.2.
MSX-DOS and the extended BASIC with 3½-inch floppy disk support were simultaneously developed by Microsoft and ASCII Corporation as a software and hardware standard for the MSX home computer standard, to add disk capabilities to BASIC and to give the system a cheaper software medium than Memory Cartridges, and a more powerful storage system than cassette tape.
MSX-DOS was binary compatible with CP/M-80, allowing the MSX computer to easily have access to its vast library of software available for a very small cost for the time.
At initial startup, COMMAND.COM looks for an optional batch file named AUTOEXEC.BAT and, if it exists, executes the commands specified in there.
[5] 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.
[6] Chris Larson from Microsoft and Jay Suzuki visited Paterson in Seattle at the end of February and early March 1984.
They got everything working and on April 23, 1984, Microsoft accepted delivery and made the final payment for MSX-DOS to Paterson.
To be able to run (slightly modified) CP/M software Microsoft decided to implement functionality similar to major parts of the CP/M BIOS, routines that CP/M systems used to do specific disk operating tasks, such as opening files, etc.
This ensured that MSX-DOS floppies could be used on an MS-DOS machine, and that only one single formatting and filing system would be used.
Microsoft also added a standard set of disk commands to MSX-DOS that were compatible with MS-DOS but not with CP/M.
The resulting DOS was a system that was much user-friendlier than CP/M, but was (in principle) compatible with major CP/M software packages such as WordStar, Turbo Pascal and the "M80" assembler and "L80" linker.