CODEWITHSUNDEEP
windowscomexecutable
Kei Nivky
Kei Nivky

Reputation: 377

Execution of COM files in windows

Just curious about how windows handles COM executables. Does it reserves the first 64kb of physical memory to them? If so, is that segment always inaccessible by other programs?

Any material on the subject is appreciated.

Upvotes: 2

Views: 538

Answers (2)

John
John

Reputation: 5635

32-bit windows will execute them inside ntvdm.exe (which emulates DOS / 16-bit windows) 64-bit windows does not support 16-bit applications

If the file is actually a valid PE executable (in other words a .EXE that was renamed to .COM) then it will run as a Windows application.

Upvotes: 1

Hans Passant
Hans Passant

Reputation: 941455

You have to be talking about the old .com MS-Dos executable file format. No, they run in a virtual machine implemented by ntvdm.exe. It takes advantage of virtual 8086 mode, implemented by the processor. An execution mode that emulates a 16-bit 8086 processor. Follow the link to learn more about it.

Upvotes: 1

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