Killer Instinct (SNES)

Killer Instinct
Developer: Rare Publisher: Nintendo Platform: SNES Released in US: August 30, 1995 Released in EU: September 21, 1995 This game has anti-piracy features.

Anti-Piracy

A number of anti-piracy measures exist, sharing many of the same routines used in Donkey Kong Country 2 and 3.

Failing any of the below tests will write the string I PiRatE to RAM address $7E0200 and then display the above unauthorized device message on boot up.

Boot State Test

Almost immediately after booting, the Emulation Flag and Direct Page register are examined. The console already being in Native Mode and/or the Direct Page register containing a non-zero value fails the test as these are evidence that another program (e.g., a backup unit menu) was running before the game had a chance to boot.

Stack Test

If the Reset Vector was at the top of the stack, the test fails. Explained in more detail in the next section.

RAM Tests

The beginning of RAM (range $7E0000-7E1FFF) is searched for three types of fingerprints left behind by the unauthorized devices. The two jump tests, along with the stack test mentioned in the previous section, are looking for the various methods that attached hardware can use to switch from its programming to that of the game cartridge.

Jump $4C

Checks for operation $4Cxxxx, where xxxx is the Reset Vector.

Indirect Jump $6C

Checks for operation $6CFCFF, an indirect jump.

Incrementing RAM Pattern

Checks for the incrementing 32 byte string $60-7F (i.e., 60,61,62 ... 7D,7E,7F). This includes lowercase ASCII characters a-z.