How to DualBoot Mac Versions on a Silicon Chipset Mac. (Any Type of Mac.)

I made 2 versions of macOS running on my Mac. It's great for working on different prongams that are too old to run on macOS Sonoma(macOS 14)

You need at least...

Enough Storage space

Correct chipset(if you want to run your OS, I'm installing macOS)

A USB drive that can install your OS.

Now go to Disk Uititly and partion your mac HD. Erase it a APFS. (You can Format it during Windows or Linux installitation.)

Now you must make a bootable installer to install your OS.(I will not list the steps to make the USB. Find out on your own)

After that is done restart your Mac.

M1/M2/M3 chipset, hold the power button once you see the apple logo. It will shutdown. Realse and hold untill it says Loading startup options... then boot into your USB.