invalid drive with CDROM

my brother has a cdrom installed with specified drive D. It works fine in windows, but when he exits to DOS, and tries to change to drive D, he gets the message: invalid drive specification.

Dhoff, the CD needs to have the DOS drivers loaded so that it is accessible from DOS. It's likely that the CD came with a floppy that has those drivers, and a readme file that shows how they are to be installed.

There is one line needed in the AUTOEXEC.BAT. Here is mine:

MSCDEX.EXE /D:NCI000 /V

There is one line needed in the CONFIG.SYS file. Here is mine:

DEVICE=aoatapi.SYS /D:NCI000 /L:X

Your brother's will be similar to this, but likely a little different...

Are you selecting dos prompt from the program menu? If so it should work. Check device manager and look for ! on the hard drive controllers. Sometimes windows has a problem if you load mscdex through the autoexec.bat file. If you are pressing F8 on boot and selecting command prompt only you will need to load the drivers through the config.sys and autoexec.bator better yet rem out the mscdex line in autoexec.bat and just type the line in when boot boot up as command prompt only. If you are pressing F8 on boot and selecting safe mode command prompt only it will not load any drivers as this will bypass your boot files. One more thing to try. Boot up in safe mode. Go to device manager and remove all duplicates. DO NOT remove duplicate hard drive controllers this way {these are a lot more difficult to deal with} and there should be duplicates in system devices leave these alone also.

Hi dhoff2!
You are obviously running Windows 95. The CONFIG.SYS file must have the CDROM driver loaded for you to use the CDROM in pure DOS mode. Having the MSCDEX line in the AUTOEXEC.BAT will allow access at DOS level and in Windows, but will cause problems in Windows. That line should be in a file:
C:\WINDOWS\DOSSTART.BAT
which is executed when you select DOS Mode from the Shut Down menu. If it is not in either, the CDROM will only be available in Windows.

For more info go to this page: CDROM INFO.

If you need DOS mode often, I recommend setting up a Boot Menu.

Dennis