What exactly is the SysWow64 folder

64-bit Windows doesn't simply compile everything into 64-bit. Regarding what a 64-bit CPU should look like, Intel and AMD had their own plans. AMD's answer is straightforward: the new 64-bit processor should be able to maintain compatibility with 32-bit applications while increasing processing power. Intel hopes to take this opportunity to design the next generation of processors to be more perfect. So, there is AMD's x86-64 (later called amd64) processor and Intel's IA-64 (Itanium) processor. Unlike amd64, Itanium processors do not provide good support for 32-bit applications. The specific information, the reader should be easy to find on the Internet, it will not say much.
As an operating system, Windows naturally hopes that users can run various 32-bit applications as before, while running a 64-bit operating system. This is relatively easy to do on the amd64 processor. And Itanium is almost another matter. (Later later, Intel also produced an amd64-compatible processor, but that was a postscript.)
Although I said "relatively" is easy to do, it is not an empty glove. When the operating system is running on 64-bit, how can I guarantee that an existing 32-bit application thinks it is still running on a 32-bit system? Microsoft's solution is: Wow64, the full name is 32bit Windows On 64bit Windows (32-bit Windows on 64-bit Windows).
You can also understand that although the whole system is running in 64-bit mode, if one program is 32-bit, Windows will load a "32-bit Windows" on a 64-bit basis. In this way, the 32-bit application thinks it is running on a 32-bit system.
So, you can also imagine, this means that 64-bit Windows, not only with the system files that the 64-bit operating system should have, but also with the system files that 32-bit systems should have.
All we know is that the main system files of the Windows system are placed in a folder called System32. In order to be able to drop two sets of system files at the same time, Windows will add a folder called SysWow64 on the 64-bit system.
This has a problem, System32 and SysWow64, which put 64-bit system files, which put 32-bit system files?
If you remember that Wow64 refers to 32-bit Windows on 64-bit Windows, then you can think of a 32-bit system file in SysWow64. But you may also ask, why is a folder called System32 loaded with 64-bit system files, and a folder called SysWow64 is a 32-bit system file? Since it is a 64-bit system, why can't I have a folder like System64 and System32?
This question is very good. The answer is also very simple: people are in the rivers and lakes, unable to help themselves.
Compatibility
If I ask you, how many chances have you ever had access to the Itanium processor? I think, for the average person, there should be no. Then why amd64 will be popular, but the Itanium processor is little known? Or because of a key concept in hardware and software design: compatibility.
It is because of the Itanium processor that it has not provided good support for the existing 32-bit system, so it has been on the edge of the market. This is the same reason that you won't buy a HDTV that doesn't see the analog signal channel.
The compatibility we talked about before refers to compatibility with existing 32-bit applications on 64-bit Windows. Now consider another compatibility.
If you write a very good 32-bit application, now you want to turn it into a 64-bit application to take full advantage of the new processing power of 64-bit processors. You must think that this is not the end of the 64-bit compiler to compile it again? Maybe you find that this is not a reality of bone. You suddenly found out that in your program, for some reason you can't think of it, write the System32 folder to your program. And this 32 in System32 makes you very upset. You tried to run your program and found everything working. why? Because this is another compatibility effort for Windows systems: let an existing 32-bit application be compiled into a 64-bit application and 64-bit Windows without modification or modification as little as possible. run. In fact, it is not a case to write a path such as System32 in the program. So, in order to ensure that these applications can smoothly transition to 64-bit, Windows finally decided to put 64-bit system files in the System32 folder. And let the 32-bit system files move to SysWow64.
You will definitely think, after the 32-bit move to SysWow64, what about System32 that writes in 32-bit applications? A: Windows will give them a turn to SysWow64. Isn't that the same for System32 in 64-bit to System64? Really the same? Not the same? Really the same? Not the same? It's really different.
As a 64-bit Windows operating system, of course, I hope to make full use of the potential of 64-bit processors to make applications run more efficiently. If you are running a 64-bit application, always check if you need to turn, which will affect the efficiency of the program. Therefore, you can't make unnecessary changes to 64-bit applications. If you have to turn, you can only switch to 32-bit applications. Yes, there is no way, in a 64-bit operating system, 32-bit applications have to make some small sacrifices.
In addition, in order to ensure that 32-bit applications do not conflict with 64-bit applications, in addition to the System32 folder, the registry also needs to provide two sets for 32-bit and 64-bit, and also need to make 32-bit applications necessary. Redirected.
Conclusion
So the SysWow64 folder is 64-bit Windows, which is used to store 32-bit Windows system files.
Postscript
Compatibility is an important thing. Of course, it is also a very interesting thing. If you run "winver" in Windows 7, you will find that Windows 7 was originally Windows 6.1. why? This is the case, Windows XP is Windows 5.2, Windows Vista has become 6.0, and as a result, many applications just check the first bit of the operating system version number and find that it is not 5, so the user is prompted to say: "We do not support Windows XP previous system & rdquo;. This is also a lesson learned from the unsuccessful Windows Vista. Maybe, there will never be Windows 7.0 in the future.