Yes, it is possible to dual boot UEFI and BIOS operating systems.
Yes, it is possible to dual boot UEFI and BIOS operating systems.
You can dual boot Windows 7 and Windows 10 from your SSD without changing the UEFI settings. Just ensure you have a compatible boot configuration that includes both operating systems, and verify the MBR partition type is correct for your hardware.
UEFI includes a "legacy mode," but generally you can't use the motherboard to boot from both BIOS and UEFI simultaneously.
It depends on whether your system has multiple drives because a hard drive must be either GPT or MBR, depending on the situation. Having two physical drives works if you're using them correctly.
The CPU will first run the BIOS/UEFI setup. It’s built into the hardware. You’d need another firmware to handle that switch, assuming a legacy BIOS version is available. Look for the Legacy Boot option on your motherboard and try booting Windows 7 from there.
Some motherboards (particularly nicer ones) will use UEFI, then switch to legacy if no boot able media is found. That's as good as you'll get. Could you explain why you don't want Windows 7 on GPT? Maybe we can help you there.
The system allows this setup. I require an MBR for my Windows 7 operating system since the program I'm attempting to use needs it in a non-GPT partition. This configuration seems fixed by design.
What are you really aiming for? I’m running a triple boot setup with Windows 7, Windows 10, and Ubuntu from my main NVMe drive, plus a second SATA SSD for the Hackintosh build. Most modern UEFI BIOS support legacy booting, but that’s only relevant if you’re using an old MBR hard drive. You can boot in MBR or GPT, so I’m not sure why you’re adding this artificial restriction.