Hi, I am running Windows 7, 64bit. I downloaded and extracted FASM recently and was able to compile the HELLO.ASM file from the EXAMPLES folder.

It contains the line . But if I leave the header as in my 64bit system, it still compiles without any erros.

Now I do know from past experience that when you install a 32bit program in a 64bit OS, it still works, but 64bit programs are supposed to run faster. Is it the same for programming? I can forget about the 64bit headers and always use 32bit ones, but they will just be a little slower?

Some might suggest to look at the documentation for programming in Windows, but its really complicated and contains a lot of terms I don't understand yet.

Looking forward to your responces. Thanks in advance.

You will have to test your programs to see which are faster using 64-bit code. Sometimes programs are faster, sometimes they are slower. It depends upon what they actually do.

But either will always work? Or do I have to worry about compilation errors BECAUSE I used 32bit header/s in my 64bit system in some cases?

Either will always work. fasm does not use any headers from your system. All included files are supplied by you or with fasm.

Then I suppose it is usually better to use 64bit headers in a 64bit system. I should make it a habit to avoid 32bit headers in general, UNLESS there is an explicit reason to use them.

I would suggest the opposite. Use 32-bit code unless you have a specific reason to need 64-bit.

In general, 32-bit is both easier to write, and "faster" (as in more efficient) for most workloads.

But, anyhow, always test your code in both cases to see what works for your situation.

I don't really wanna bother with testing code speed again and again. I think I'll just take your word for it when you say In general, 32-bit is both easier to write, and "faster" (as in more efficient) for most workloads. Thank you for your help revolution.

Special advantage is that 32-bit code runs both on 32- and 64-bit systems while 64-bit code is specifically limited to 64-bit systems.