Emulating classic video games on modern PCs has come a long way in the past decade. Back then the emulation community focused on emulating games from older consoles and not aiming to simply play the newest games for free. Today the emulation world is filled with children begging for "teh romz" and websites that claim to have every video game ever made (and some that aren't even finished yet) up for free download in exchange for passing through a barrage of pop-up ads and banners for illegal software and pornography. It wasn't always this way.
In the late 1990s when accurate Super NES and Sega Genesis emulation was all the rage in the emulation world, emulation enthusiasts ran into a problem when they attempted to dump the contents of the Sonic & Knuckles lock-on cartridge when it was joined to Sonic The Hedgehog 3 and Sonic the Hedgehog 2. The copying tools could not handle the large size of the combined games. It took some ingenuity to figure out just how to join the two games on a computer, and while today playing these games is as simple as purchasing Sonic Mega Collection or illegally downloading the full versions of these games from one of those aforementioned archives, back then people had to lock the games together themselves as data. Relive those old days with the Lock-on Technology Hacking Guide which explains just how the old lock-on technology works. There are no downloadable ROMs at the end of the rainbow here, just an interesting technical article. Freebie-beggars need not apply.