Is there a
debug.exe equivalent for Windows7 where I can write machine code and see what results they have after execution?
Well, if you are looking only for Windows 7 then you can use WinDBG debugger which is available for both 32-bit and 64-bit Windows. You have to learn it and just search on Google for WinDBG tutorial/commands and you will get them.
You can also use OllyDbg but I'm not sure it will work on Windows 7 or not, as they have not mention it on their main page and they have just reported that it works like a charm on XP.
You can also take a look on PEBrowse Professional Interactive. Which has two versions
PEBrowseDbg64 Interactive(v3.2) is a 64-bit executable and requires the .NET framework. It will debug Win32/Win64 executables, managed (.NET) and/or native.
PEBrowse Professional Interactive (v9.3.3) is a debugger for Microsoft Windows 2000, Windows XP, Windows 2003, Windows Vista32, and Windows 7.
A very good way if you really miss it set up a virtual machine and use XP Mode in Windows 7 and you can use debug.exe in that way easily. As this question has end with the same solution of VM.
I've heard that it's in the 32 bit version of win7 but not the 64 but I can't confirm as I use 64. Are you trying to write assembly or machine code? I'm not sure what debug does, whether it's machine code or assembly. Try out WinAsm if it's assembly you're trying to learn/use. It's a free IDE I've used recently.
Added by Barlop
What you heard is right. The following is from Win 7 32bit, debug is available. Debug is not available in Win 7 64bit. Below is a screenshot from Win 7 32bit. (version of win7 tested on is win7 ultimate)