Will a Visual Basic 6 program run on a 64-bit machine?

Question

I have a program built with VB6 and using some 32-bit DLL's. Will this program run on a 64-bit machine? This page suggests that it should run fine on the Windows on Windows layer, but what about the DLL's?

Answer 1

Yes, both the VB 6 program and the DLLs will work just fine on a 64-bit version of Windows.

Since both are 32-bit, they will run under the Windows-on-Windows 64 (WoW64) subsystem, which effectively emulates a 32-bit operating system on the 64-bit versions of Windows.

I've run many such programs myself with nary a hitch.

Beyond Explorer extensions and kernel mode drivers (neither of which you've written in VB 6), any compatibility problems that you might experience are almost certainly the result of bugs in your own code, which are easily fixed upon detection. Ask more questions about that when you find them.

Answer 2

Are the DLLs built with VB6 as well? Or are they native?

If you are dealing with 100% VB6, then in my experience, yes they tend to run with minimal problems (I maintained a number of plug-ins for another program that were mostly implemented as VB6 COM components, around the time that Windows 7 came out).

It will all of course depend on what libraries your code is using, whether or not you are accessing locations such as %PROGRAMFILES% etc, calling code in native libraries. These things can cause small problems but it is possible to work around them.