This page is to help you install YiffOS when your computer doesn't support UEFI.
This guide assumes you are fairly comfortable with the command line and can make bootable media yourself.
You will need two different live environments: the Yiffy-Arch one and Linux Mint (or any other distro that includes boot repair; Linux Mint just makes it easier).
WARNING: IT IS NOT ENCOURAGED YOU DO THIS AS THERE IS NO OFFICIAL SUPPORT FOR THIS AND I WILL NOT HELP YOU!
Now that you know the risks of doing this, we can get started!
First things first, you'll need the installation media that supports Legacy (BIOS) booting.
Get the Yiffy-Arch ISO hereNow all you have to do is use a tool like Rufus (Windows) or DD (Linux) to put it on a USB.
Obviously, you'll need to boot from the Yiffy-Arch media now. It will look just like an Arch Linux ISO.
Once it's booted and you have access to the terminal, run chmod +x /usr/bin/bulge since the ISO maker messed up the permissions for bulge. You can check if it worked by running bulge i neofetch, which should install neofetch. If you run neofetch now, you will see a cursed screen indicating that you've altered your ISO by installing a package with bulge... /j
Now that you have bulge working, you need to set up your drives to install the funny OS. Use fdisk (or whatever you prefer) to create your first partition of 1GB and your second partition with the remaining space. Format both to ext4 (or your favorite filesystem) using mkfs.ext4 /dev/sdX1 and mkfs.ext4 /dev/sdX2 (adjust for your partitions).
Now that your drive is ready, run curl -O https://stick.moe/yiffos/install-yiffos-bios.sh, then chmod +x ./install-yiffos-bios.sh, and finally ./install-yiffos-bios.sh /dev/sdX1 /dev/sdX2. This will start the installation of the actual OS. Be patient; it may take a while.
After it finishes installing, you need to boot into the Linux Mint drive and run drive repair. Go into the Advanced Options drop down and make sure that you do not purge GRUB before reinstalling. At this point, if you have an Nvidia GPU you can add the nomodeset kenel perams so you can boot the system (it'll hang without it). You can ignore the peram is your a based AMD GPU user.
It will yell at you and say it failed. It did not fail. Reboot the system and you should be able to get in.
Now, you get to enjoy your broken ass system!
For help with the certs, go to this site