How to make bootable CDROM or USB from floppy? I have a bootable floppy that boots just fine on old PCs.
I want to boot it however on my 2015 Macbook Pro, which does not have the BIOS (whereas my 2013 MBP did).
So I cannot on the 2015 model even boot a Linux CD.

I have an ISO header that will let me create a readable CDROM, but not a bootable CDROM. (Command is: cat isoheader.img floppy.img > cdrom.iso)

The Apple bless command gives an error when I add the --legacy switch.

What to do?

PS: I cannot use bootcamp as I do not have enough free drive space.
If you don't have the ISO use disk utility to take an image of your floppy. 
Use the app from etcher.io to "burn" this ISO to a USB drive. 


Now if the image itself is not bootable, that might be a better answered on a different stack-exchange.