How do I get the iPod OS?

Last summer I bought an iPod A1019 Second Gen Classic from a garage sale for about $10 USD, I hunted down the firewire (which apple actually sold, by Belkin) connected to my mac. but iTunes does not recognize and the iPod screen when booted shows a folder with a question mark. It appears to not have the iPod OS on it. Its there a way to get the iPod OS for this iPod model? I have tried various restore options and none have worked. I have only found files, and documents online for windows users. I have seen drivers for it but they are all windows. I have a mac and therefore need a file that can be opened to install the software on the iPod by using a mac, not an .exe. All I have been able to find are .exe files.