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hi,

im reading about the signatures required to create a boot disk. this information is all in the context of a "floppy disk" image. what is the reason floppy images are preferred? is it not possible to do this as a CD image (an .iso?)?. i thought floppy images were a thing of the 90's. my PC doesnt even have a floppy drive. i know development is typically done using a VM, but why the preference for a floppy anyway?

i have a goal to make a boot cd that i can boot my physical pc with and load a "kernel" that says "hello, world!" (just to get my hands dirty). im obviously missing something i just dont know what it is. why cant i write the boot code straight to cd rom without thinking about floppy drives?

bonch wrote:hi,

im reading about the signatures required to create a boot disk. this information is all in the context of a "floppy disk" image. what is the reason floppy images are preferred? is it not possible to do this as a CD image (an .iso?)?. i thought floppy images were a thing of the 90's. my PC doesnt even have a floppy drive. i know development is typically done using a VM, but why the preference for a floppy anyway?

i have a goal to make a boot cd that i can boot my physical pc with and load a "kernel" that says "hello, world!" (just to get my hands dirty). im obviously missing something i just dont know what it is. why cant i write the boot code straight to cd rom without thinking about floppy drives?

I'm not sure what you are missing. What have you done so far ? Where are you stuck ?

Of course you can.

There are several things to take into account.

For one, a significant amount of stuff in the Wiki tutorials is ancient (as in, over ten years old). That doesn't mean it is wrong, or does not apply anymore, just that sometimes stuff hasn't been updated as well as it should.

Two, while it doesn't make much difference if you are running a VM (using image files), a real floppy is re-writeable, and much better so than a CD-RW. Given the tight edit-compile-test-edit cycle, "real" floppies are preferable over "real" CD-RW for this reason.

Three, writing a floppy driver (to get at "the rest" of the OS) is simpler than writing a CD-ROM driver.

Four, it is possible to use a floppy image on a CD (boot floppy emulation, as shown in Bootable CD), so up to the point where your OS doesn't fit on a floppy (or you don't want to use a floppy image for stylistic reasons), knowing how to create a floppy image serves both worlds.

That all being said, there is the Bootable El-Torito CD with GRUB Legacy tutorial, which shows how to create just what you want: A bootable CD image without using a floppy image.

ahh got it. thanks Solar.

You could also use the floppy 2.0, sometimes its called USB. A full USB stack to support all features of USB is a bit more work then supporting floppy, but then you have something.

Bietje wrote:a bit more work

Your understatement has been noted.

Combuster wrote:

Bietje wrote:a bit more work

Your understatement has been noted.

Sorry hahah

But just read and writes are 'do-able'.