MS-DOS 2.00

MS-DOS 2.0 began life as a project called XEDOS, intended to be an single user intermediate operating system between the original MS-DOS and XENIX, Microsoft's flavor of UNIX. As a result, MS-DOS 2.0 inherits UNIX piping, file handles and system calls and a general UNIX-style API from the XEDOS project. Additional improvements over 1.0 include support for hard drives up to 10MB in size (16 MB or 32 MB for some OEM versions of formatting tools), as well as support for a tree-based file system with subdirectories, user installable device drivers, non-multitasking child processes, environment variables, FOR and GOTO loops in batch files and an improved TSR API. It also added support for a new 9-sector disk format that extended floppy disk capacity to 360KB (3.5-inch, double-density 720KB floppy disks were also supported with some OEM releases). MS-DOS 2.0 would also depute with the IBM PC-XT as PC-DOS 2.0.

MS-DOS 2.0 also contained two undocumented config.sys settings, SWICHAR and AVAILDEV which change the command argument character from a forward slash (/) to a dash (-) and changed the directory separator from a back slash (\) to a forward slash (/). Both settings made MS-DOS 2.0 more UNIX-like but were never fully implemented and caused issues when used with certain programs. As a result, they were removed from MS-DOS 3.0 and onwards.