Creating a NO-CD file for Games
If you find the place where a game checks CD and you know which jump has to be changed, then you have to remember

following information:
**You want to jump: change a jump to a unconditional jump
( EB - short jump, E9 - medium jump, EA - far jump ).
DON'T CHANGE JUMP TO OPPOSITE ( 74 <-> 75 ),
because when you insert CD a game doesn't run.
**You don't want to jump: change a jump to some instruction
(4048 - push ax, pop ax ).
DON'T CHANGE TO 90=NOP, because this value is checked by
some programs. If a game show small window with information
"Please insert CD", it's done by "MessageBoxA"
API function. Go to your favorite debugger and catch the window.
In SoftICE you have to type: bpx MessageBoxA

The most popular API functions used to check CD are:
- GetDriveTypeA
- GetVolumeInformationA
- GetDriveAttributeA
- FindFirstFileA
- SetCurrentDirectoryA
- GetFileSize
- CreateFileA
- GetDiskFreespaceA
- GetFileAttributeA
- mciSendCommandA & mciSendStringA (used to check AudioCD)
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