I would like to dual boot my computer. Currently, I am running windows 10 64bit, so I would like to run windows 10 32 bit for legacy programs. The first step is to buy another copy of windows 10 32bit. The next step is to ensure that I have hard drive space for the installation. Can anyone point me to a video or other tutorial as to the next steps?
Thanks in advance - F.
You can do it via re-partioning and Windows multi-boot options, but the easiest and least disruptive way of doing it is if your BIOS supports the option of multiple boot devices. On one of my older computers, I was running Windows XP and decided to install Windows 7. I did it just by adding a small SSD on which I installed Windows 7. I switch between the systems at the BIOS level by hitting the appropriate key to get into the “BIOS boot device” mode, and selecting the device.
You could also consider another simple solution, other than Windows dual-boot. You can install a free copy of VMware (VMware Workstation Player) and install your 32-bit version of Windows in a VM. Data can be exchanged between the VM environment and the rest of the world through the VMshare folder. But this is only practical if your use of the 32-bit apps is relatively infrequent.
ETA: Windows 10 64-bit will surely run 32-bit apps? Perhaps you mean you need to run 16-bit apps?
Before you try dual booting, I would recommend trying out OTVDM. It is an open source project based on Wine that allows 16-bit Windows apps to run on 64-bit Windows.
The installer isn’t the most user-friendly, so I’ll tell you how to install it:
After that, any time you try to open a 16-bit application, OTDVM will take over and run it instead. It works just like the NTDVM which is how 32-bit Windows can run 16-bit applications.
Compatibility is not perfect, of course. But, if it works, it’s a lot easier than dual booting, and easier than having to fire up a virtual machine.
As far as I can remember creating a dual boot system is quite easy.
You need to create a new partiton on your system drive, or use a different drive, and when installing you choose where to put the new install, select the new partition.
Many helpful sites on Internet just Google “install dual boot on windows 10”[Google results](https://install dual boot on windows 10)
On start up with the dual boot you have the option of which system you want to use .
You can change priority if you wish.
Hope this helps 
Mac has dual boot programs like Parallels that let you run both OSes simultaneously. Is there something like that for PC?
I would use a VM.
And I am really curious what software will run on win 10 32-bit but not on win 10 64-bit?
There’s VMWare if you want a commercial solution. Oracle VirtualBox, which is free software. Microsoft itself has Hyper-V. If you’re looking to run DOS software (mostly old games) there’s DOSBox. To run native Linux ELF binaries on Windows you can install Windows Subsystem for Linux.
Really old 16-bit software, since 64-bit Windows does not have a virtual machine capable of running 16-bit software. See the instructions posted by @BigT above for OTVDM, which will run your 16-bit software (maybe) on 64-bit Windows.
Needing to run a 16bit program is the only use case I can think of. You can absolutely do this but if it was me I’d try virtualizing a 32bit installation first. It’s much easier and faster to open a virtualization window vs rebooting the whole machine.