Pre-requisites check in installshield script

I am creating a Installscript MSI project using Installshield 2014 profession edition. I want to check following things in installshield project as pre-requisites before continuing installtion:

• OS either windows 7 & above OR Windows 2008 R2 & above
• Core i3 processor
• Minimum free disk space 10gb
• ODAC 11g - should be checked for existence and should not be forced to install
• IIS 7.5 & above

I tried to set conditions for OS, RAM in 'Install conditions' from General section. There, I cannot set other conditions. Additionally I want to write a log file which will contain information about what prerequisites are not met during installation.

Could anyone please suggest how this could be done using Installscript?

Any help is really appreciable.

Thanks in advance.

I got solution for checking OS, minimum disk space and IIS version.

To check OS version: In Installscript, I used SYSINFO structure to check value for member nISOSL. Its value indicates the operating system of the target machine.

To check free disk space: I used following couple of statements to get free hard disk space.

nvHDDFreeSpace = GetDiskSpaceEx("C:", GBYTES);
NumToStr(szMsg, nvHDDFreeSpace);

To find IIS version: Following registry path can be visited to get IIS major and minor versions:

SYSTEM\CurrentControlSet\Services\W3SVC\Parameters