Ages ago, I tried out Puppy Linux, that ran from a burned CD. If I made updates, it wrote another filesystem extent to the disc, and I think the loading process

Ages ago, I tried out Puppy Linux, that ran from a burned CD. If I made updates, it wrote another filesystem extent to the disc, and I think the loading process just used those to over-write files as needed until the boot completed. I was thinking of it for a home firewall at the time, but in any case, it made for a very ephemeral system.