MSCDEX

MSCDEX or Microsoft MS-DOS CD-ROM Extensions is a software program produced by Microsoft and included with MS-DOS 6.x and certain versions of Microsoft Windows. Earlier versions of MSCDEX were installable add-ons beginning with MSDOS 3.1.

It is a driver executable which allows DOS programs to recognize, read, and control CD-ROMs using the ISO 9660 file system. This requires the previous loading of an appropriate CD-ROM device driver (example: OAKCDROM.SYS), usually from CONFIG.SYS. The program was used up until Windows 95 when it was replaced by the 32-bit version CDFS.