http://macfaq.org/software/macos.shtml#Q1.1.6
It's reasonably common that someone gets an old used Mac and it has no operating system on it. Often, these people don't have anything other than a PC to access the Internet. As long as your Mac is an SE FDHD or Mac IIx or higher, you can use these directions compiled by Alex Harrington (aka "fastkeys" ) to get that Mac up and running. Due to irreconcilable physical differences in the floppy drives of PCs and Macs, a Mac 128, 512, Plus, original SE, or un-upgraded II cannot use this procedure. If you have one of these, you'll need to get a Mac that can read PC floppies or find someone willing to make floppies for you.
je pense que je suis dans ce cas