This is my first post, so excuse anything that isn't normal on the computercraft forums. this is a multi-OS bootloader, based on Opus OS's bootloader system, meaning it's pretty simple to modify and should work if you already have Opus OS installed. I only edited the original program, I'm not claiming it as my own, if you want to help the origingal creator, Click here, their full OS is way better. (https://github.com/kepler155c/opus) to install type what's below
pastebin run kCG6gXy6
EDIT: Fixed the boot option glitch where added options from the startupoptions.txt file don't appear, edit now opens the startup file itself, and I removed the download for the startupoptions.txt file.
EDIT 2: Added splash screen, New name is BootR
EDIT 3: just wanted to say, I'm working on a new project ;)
EDIT 4: Now pulls from easy-to-edit+understand boot list file.