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Older 16-bit applications are run using NTVDM in Windows NT based OS (2000, XP, Vista, 7). NTVDM is not included in 64-bit editions of Windows.
As such you cannot run 16-bit applications in any of the 64-bit editions of Windows.
You can try installing an older 32-bit edition of Windows (like Windows 98) inside a virtual machine using Virtual PC
or Virtual Box
. Then install your older Cobol inside this Windows 98.