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Why Does Microsoft Still Offer a 32-bit OS? (backblaze.com)
Brian Wilson, a founder of cloud storage service BackBlaze, writes in a blog post: Moving over to a 64-bit OS allows your laptop to run BOTH the old compatible 32-bit processes and also the new 64-bit processes. In other words, there is zero downside (and there are gigantic upsides). Because there is zero downside, the first time it could, Apple shipped with 64-bit OS support. Apple did not give customers the option of "turning off all 64-bit programs." Apple first shipped 64-bit support in OS X 10.6 Snow Leopard in 2009. This was so successful that Apple shipped all future Operating Systems configured to support both 64-bit and 32-bit processes. All of them. But let's contrast the Apple approach with that of Microsoft. Microsoft offers a 64-bit OS in Windows 10 that runs all 64-bit and all 32-bit programs. This is a valid choice of an Operating System. The problem is Microsoft ALSO gives customers the option to install 32-bit Windows 10 which will not run 64-bit programs. That's crazy. Another advantage of the 64-bit version of Windows is security. There are a variety of security features such as ASLR (Address Space Layout Randomization) that work best in 64-bits. The 32-bit version is inherently less secure. By choosing 32-bit Windows 10 a customer is literally choosing a lower performance, LOWER SECURITY, Operating System that is artificially hobbled to not run all software. My problem is this: Backblaze, like any good technology vendor, wants to be easy to use and friendly. In this case, that means we need to quietly, invisibly, continue to support BOTH the 32-bit and the 64-bit versions of every Microsoft OS they release. And we'll probably need to do this for at least 5 years AFTER Microsoft officially retires the 32-bit only version of their operating system.
It's not rocket science - many people still use PCs that have 32-bit processors.
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THIS! Add to that the fact that some business only run 32bit legacy software and running a 64bit OS would do nothing but add overhead.
Microsoft supports legacy computers and software much better than Apple does.
Heck, I got a request today for a Windows XP ISO to rebuild a PC that runs machine control software.. (And no, it not connected to a network.)
Some software just won't run in a 64 bit environment, regardless of WoW64 and thunking. Most of the software that is the most rigidly tied to a 32 bit environment is the kind of software that is also the most mission critical. The kind of software that operates radar ARPAs, hospital respirators, navigation systems, and MRIs. Apple, as pretty as it is, just doesn't have the presence in the industrial side of things that Microsoft does - in fact they don't have any industrial presence to speak of. As a desktop only computer, they are more free to adopt new OS features that render old software incompatible. Many beloved programs from the past have been rendered inoperable by a MacOS upgrade. While inconvenient for the user, it is hardly catastrophic.
Now, no one is going to perform an OS upgrade on an existing MRI of course. But there are many reasons why an MRI vendor would want to bring out a new model with a new (perhaps more secure) version of Windows, but where the software is still tied to 32 bit. Industrial software is far less agile. You just can't recompile for 64 bit, it has to go through very strict verification and rigid change control. That kind of process takes years, and costs far more than most software porting. What about that 80 year old who has had a forgotten metal bit in his shoulder for 40 years who is put into an MRI to have that bit forcibly ripped out of his body by because the magnetic flux feedback detection didn't work properly when the 32-bit driver for it was mis-ported to 64 bit?
So while Microsoft is hardly a company I regularly defend, in this case you just can't compare a company that only puts out pretty ergonomic desktop machines and keeps draconian control of hardware to the extent that you really can't use the OS anywhere else, and a company that produces OSes for everyone's hardware that ranges from embedded microcontrollers, to warship navigation systems, to tablets.
CPU boots to Real mode (16-bit).
OS switches the CPU from Real to Protected mode (32-bit).
OS then switches from Protected mode (32-bit) to Long mode (64-bit).
Only Protected mode supports emulating Real mode. This emulation is called Virtual 86 mode.
And just like Protected mode emulates Real mode, Long mode emulates Protected mode.
Once in Long mode, the only way to get out of it is a hard reset.