Some games can me fooled and don't even need the CD emulated. Daggerfall, for example, will accept a SUBST directory as the CD.

I ran into a problem mounting ISO in pure DOS.
I use bat for mount :
SHCDHD86.EXE /F:MYDISK.ISO
SHSUCDX.COM /D:SHSU-CDH
Everything goes well, the image was mounted, the drive letter appeared, but when the game starts, it does not see the files from the mounted drive, the game closes and opens the norton panel, where my mounted disk should be, with an error of not being able to read it.
What can prevent this? Could it be that the data one file in the image is 148 megabytes when the system RAM is 128 ?