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[ The PC Guide | Troubleshooting and Repair Guide | The Troubleshooting Expert | Troubleshooting Specific Components | Troubleshooting CD-ROM Drives | Configuration Problems ]

My CD-ROM drive works in Windows 95 but I can't access it when I restart in MS-DOS mode

Explanation: You installed Windows 95 and the CD-ROM works properly within the graphical interface. When you reboot into DOS mode however, your CD-ROM is not accessible, making it impossible for you to use programs such as DOS-based CD-ROM games.

Diagnosis: Windows 95 uses its own driver and file system extension (equivalent of MSCDEX) to allow access to the CD-ROM drive when you are within that operating system. When you "Restart the computer in MS-DOS mode", as Microsoft euphemistically puts it, you are just shutting down Windows 95 and staying in the DOS 7 environment that underlies it. This unloads the Windows 95 CD-ROM driver, so you won't be able to access the CD-ROM drive unless you have a real-mode DOS driver and DOS MSCDEX loaded. The CD-ROM driver must be loaded when the PC starts. MSCDEX can be loaded at any time.

Warning: On some systems, loading the CD-ROM driver in CONFIG.SYS can cause conflicts with other IDE devices. If you experience this sort of problem you will not be able to load the CD-ROM driver within CONFIG.SYS and you will have to use a custom boot environment (see below) to use the CD-ROM under DOS.

Recommendation: There are two possible ways to set things up so the CD-ROM is visible in DOS. One is to load the driver at boot time and then load MSCDEX when you shut down Windows. The other is to set up a custom boot configuration for your DOS programs that will boot up with a different CONFIG.SYS and AUTOEXEC.BAT file when you want to use your programs, and then restore the "regular" Windows 95 system files when you are done. Each has its advantages and disadvantages.

  • If you do a lot of DOS gaming or have other work that requires you to access the CD-ROM a great deal from DOS, you are better off loading the DOS CD-ROM driver automatically when you boot up the PC. (Bear in mind the warning above about compatibility.) Windows 95 will use its own version of MSCDEX; you should put the DOS command to load MSCDEX into the "DOSSTART.BAT" file in your Windows directory. Then, whenever you shut down Windows to DOS ("Restart in MS-DOS mode") MSCDEX will be automatically run and you will have access to your CD-ROM drive. The only disadvantage with this is possible slightly reduced performance from using the DOS-based CD-ROM driver. (I personally don't notice any degradation from this setup.) It also takes a bit more conventional memory.

Note: If when you restart in DOS mode you see the system try to execute MSCDEX but it produces an error message about not being able to find a CD-ROM driver and you can't access the CD-ROM drive, this means that you have half of what you need set up: MSCDEX is being loaded from DOSSTART.BAT, but the actual CD-ROM driver is missing or commented out in CONFIG.SYS.

  • Another option, preferred if you rarely need to use your CD-ROM drive in DOS, is to set up a custom boot environment for each program that needs to access the CD-ROM in DOS. Here, you select the Properties for the DOS program you want, go to the "Program" tab, select "Advanced...", select "MS-DOS Mode" and then select "Specify a new MS-DOS configuration". Then you can enter a CONFIG.SYS and AUTOEXEC.BAT for that program, putting the CD-ROM driver in the CONFIG.SYS and MSCDEX in the AUTOEXEC.BAT (with appropriate parameters, of course). The advantage of this system is that your normal Windows 95 configuration is undisturbed and is left at its optimum configuration. The disadvantage is that you have to really reboot the entire PC each time you run one of these DOS programs (which gets tiring quickly if you use them a lot).

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