Arcade games are protected for the same reason as any other: piracy (specifically in the form of bootlegs – the same game adapted to run on cheaper hardware so that it could be sold to operators for less money). One of the most devious methods – unhackable until MAME – was Atari’s “Slapstic” security chip. When the game was run, the game code checked for the security board in various ways. If it wasn’t there, the game malfunctioned or refused to run. (This is similar to the hardware “dongle” protection used by some high-end PC software.) Since the security chip came only with purchased games, copies of the ROMs were unusable. This is why games like Marble Madness and Indiana Jones could previously not be emulated, though their ROMs were available. Another way to protect ROMs was to encrypt them. A custom CPU or special chips on the main board decoded (decrypted) the data as it ran the game. Copying the ROMs was futile unless the encryption system had been “broken”. As such, it is diffi
I am not a developer per se, but I have a pretty good handle on this topic. Due to hacks and bootlegs (see the above question), some manufacturers of video games come up with some devious schemes for preventing arcade operators from stealing their games. One of the most devious (and unhackable until just recently) was the slapstic board. In a nutshell, the manufacturers take a special ‘security board’ (my local operator called it a “deflector” board – basically a slapstic board) and connect it to the system board (PCB) of the game. Within the ROMs they write protection checks to ensure that the security board is actually there. If not, the game hangs. This is much akin to the gruesome ‘dongle’ protection that is still in use by some computer programming companies. Since this slapstic board only came with the ‘purchased’ version of the PCB/video game, even if the arcade operators copied the ROMs, they would be unusable in any other PCB. Games like Marble Madness and Indiana Jones used t