Dark Chip

Dark Chips are vastly powerful BattleChips that increase a NetNavi's maximum strength, but destroy its connection with its NetOp and turn the Navi into a Darkloid. Darkloids use these chips to survive. They start out using them to become more powerful, but soon become addicted and need them. After a while of addiction it starts to corrupt their data, until eventually they become so corrupted that they are deleted. In the anime Dr. Hikari says that the Dark Chips are a type of chip which trades a Navi's soul for power. They were created by Dr. Regal.

In the games, Dark Chips have several effects: First, when any number of Dark Chips have been used in battle, the user permanently loses 1 HP from their maximum HP count. Also, using a Dark Chip would result in a bug occurring on MegaMan, depending on the Dark Chip used (though most have the tendancy to cause an HP bug). Finally, when one has used enough Dark Chips, he turns "dark", losing the ability to enter Full Synchro or use Double Souls, and gains the ability to use chips exclusive only to "dark" MegaMan (like Snake or Muramasuma), DS chips, and also can enter a "berserker" state on a lethal hit. To reverse the effects of "darkness", one must enter battles without usage of Dark Chips, and this process can be sped up by the "Soul Cleanser" NCP.

In MMBN4, Dark Chips can only be used when MegaMan enters an "anxious" state, after taking several hits in succession without fighting back. They take up the last 2 slots of the Custom Screen, and cannot be used with any other chip, aside from another Dark Chip. When one is "dark" enough, he can enter the battle with Dark Chips already displaying. In MMBN5, the Dark Chips are Battle Chips on their own, with their own code. Each folder can hold up to 3 Dark Chips at one time.

In both games, Dark Chips are the most powerful and overpowered chips in the game, but the glitches they cause can discourage players from using some of them (Chaos Unison bypasses the glitch, but with a twist besides, so it is is also rather ineffective).

In the anime, the chips simply power up whatever Netnavi uses them(but it is later shown there are still dark versions of chips like Darksword and Dark Cannon), but they still turn them evil. Another side effect, likely created to coincide with the fact that permanently remove HP in the game, is that they over time delete the data of whatever Netnavi uses them. The Dark Chips were also exceedingly addictive. ProtoMan.EXE turned evil in episode 27 of Axess after Chaud slotted in an extra strong Dark Chip to fight ShadeMan.EXE, though later a cure was found for it.

Darkchips can be strongly compared to drug addiction in both games and anime in many ways. Interestingly, MegaMan can control DarkChip influence if used, but an overload of dark enegy like a Dark Chip implant or a direct infusion of dark energy will cause him to turn into MegaMan DS, who also cannot die of Dark Chips, due to the fact he was born of pure dark energy.

Trivia

 * Intense hacking in Battle Network 6/Megaman Battle Network 6 will reveal that Dark Chips were planned to be used (and this time, didn't remove HP or cause a Dark State, but inflicting an extremely fast HP bug), but the ideas seemed to have been scrapped, seeing as there are no descriptions for some chips and no icons for any Dark Chip in that game. However, the chips work fluidly and don't freeze the game.  Also, Dark Sword and Dark Thunder made a return as BugRSword (Bug Rise Sword) and BugRThunder (Bug Rise Thunder), which when used, replace MegaMan's Charge Shot at the cost of sacrificing bugs (both are Giga Chips).