64 bit vs 32 bit
Hello. Can someone help me understand a few things about 64bit vs. 32bit? I understand that one big thing about 64 bit is that it can use more RAM than a 32 bit system. That’s fine...I get it. Here's my question though: what actually happens when I am running a VISTA or Win 7 64bit installation but have 32 bit apps/games? I have not installed any of my VISTA or Win7 64bit versions because I don't know what will happen if/when I use a 32bit App/Game. Will the apps/games "NOT" work at all.....or..... will they simply just "RUN" at 32bit? Will my system crash or be damaged? Can someone please help enlighten me. Thanks.
They run in an emulation mode. See: http://en.wikipedia.org/wiki/64-bit
The vast majority of 32-bit programs run just fine in 64-bit Windows. It's a little misleading to say that it's "emulation" mode because they run using native x86 instructions - its only when they make calls to the operating system that any special handling needs to be done to interface with the 64-bit OS.
In fact there are still very few true 64-bit programs around, so that huge majority of programs that everyone uses on 64-bit windows actually 32-bit programs. This will probably continue for several years since most programs are run perfectly well in a relatively small amount of RAM and therefore there's no pressing need for then to use 64-bit code.
The big exception to all this is for device drivers. Device drivers run at the bar-metal hardware level, so they need to be 64-bit in order to run in a 64-bit OS.