Windows on Windows facts for kids
Windows on Windows (often called WOW) is a special part of Microsoft Windows NT computers. It helps older computer programs, especially those made for Windows 3.x or even earlier, run smoothly on newer versions of Windows.
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Why We Need WOW
When computers and their operating systems got more advanced, older programs sometimes stopped working. WOW was created to fix this problem. It lets many older 16-bit Windows programs run on newer 32-bit Windows without needing big changes.
This was really helpful when people were moving from older systems like Windows 3.x to Windows 95. It meant they could upgrade their computer's operating system but still use most of their old programs.
Older Windows systems, like Windows 9x, were built in a way that could easily run both old 16-bit and newer 32-bit programs. But Windows NT systems are very different. They needed a clever solution to run old programs. WOW uses two main ways to do this: "thunking" and "shimming."
How Thunking Helps Old Programs
Thunking is like having a translator for computer instructions. WOW "thunks" 16-bit instructions (the old language) into 32-bit instructions (the new language). This allows older programs to use memory and other computer parts correctly on a newer system.
Imagine old 16-bit programs usually sharing one big workspace in your computer's memory. This can sometimes cause problems if one program crashes. But WOW can also make each 16-bit program run in its own separate workspace. This helps stop programs from crashing each other, but it might use a bit more memory.
WOW is built into 32-bit versions of Windows NT. However, newer 64-bit versions of Windows (like Windows Server 2008 R2 and later) cannot run 16-bit programs directly. For those, you might need other special software, like DOSBox.
On Windows NT, a file called `WOWEXEC.EXE` helps WOW do its job. It can even make the computer act like an older Windows 3.x, Windows 95, or Windows 98 system to run very old programs.
How Shimming Fixes Problems
Sometimes, old programs have trouble with new features in Windows. For example, they might expect to save files anywhere they want. But modern systems like NTFS have special rules about where programs can save files for safety.
Another example is how files are named. Old programs might only understand short names (like `MYFILE.TXT`). Newer Windows versions use "long filenames" (like `My Important Document.txt`). Since Windows 95, the system keeps both a long and a short name for files. This way, older programs can still find and use files with their short names.
Programs that try to talk directly to the computer's hardware also won't work on newer Windows. Also, some old programs expect special setup files from DOS or Windows 9x, like `AUTOEXEC.BAT`. Even though Windows NT doesn't use these files, empty versions of them exist so old programs don't get confused.
"Shimming" is like adding a small patch or adapter to an old program. These "shims" catch the old program's requests and change them so they work correctly with the new operating system. This helps many older programs run even if they were made for a very different computer world.
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In Spanish: Windows on Windows para niños
