Making your CD-ROM drive available from DOS

Unlike Windows 9x and later versions of Windows, MS-DOS and Windows 3.x do not inherently recognize CD-ROM drives. They need to be supplied with a third-party driver for the CD-ROM drive.

First, find your CD-ROM driver disk. It should have come with the drive. If not, get one from the manufacturer. You probably won't be able to get the drive to work in DOS without this disk.

Now check out the disk and find the file on it with a .SYS extension. There'll probably be only one. This is the drive's DOS device driver. (Note that if you view the driver disk in Windows Explorer, you may not be able to see the file because Explorer hides files with a .SYS extension by default.)

Copy the .SYS file to your boot disk's root directory (usually, your boot disk is your hard disk unless you're using a boot floppy). Then add a line to your CONFIG.SYS which looks like this:


(Of course, use the actual driver file's name instead of DRVRNAME.SYS.) The text after the /D: switch is the actual device name that will be loaded into resident memory. You can make this anything you want, although in typical usage, the first CD-ROM drive's driver got a device name of MSCD000, the second one was MSCD001, and so on.

Once that's done, add a line to your AUTOEXEC.BAT which looks like this:

MSCDEX /V /D:MSCD000 /M:10

Your CD-ROM drive should now be available in DOS when you reboot.

MSCDEX.EXE is a standard DOS/Windows command which comes with the operating system, although of course it didn't come with earlier versions of DOS either, meaning you may need to get MSCDEX.EXE as well if it didn't come with your OS.

In the event that your CD-ROM drive did not come with a DOS driver (unfortunately, most don't these days), you may be able to get the drive to work using one of the "generic" drivers which come with Windows. There are four (4) of them, and their file names are ASPICD.SYS, OAKCDROM.SYS, BTCDROM.SYS, and FLASHPT.SYS. Most CD-ROM drives from the DOS era can be made to work in DOS with one of these drivers.

Once you've gotten your CD-ROM drive working in DOS, you may find that the device driver plus MSCDEX take up a lot of memory when loaded. To free up some memory when you're not using these drivers, I would recommend commenting out the lines for these items in your CONFIG.SYS and AUTOEXEC.BAT files by adding "REM " (including the space at the end) at the beginning of each line, then rebooting. This will cause the lines to not run, and is preferable to deleting the lines entirely, since when you want your CD-ROM drive available again, you can simply delete the REMs and reboot instead of having to enter the entire lines into the configuration files again.

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