Duel disks

DiaDhank
The Sacred Guardians readying their DiaDhanks.The Duel Disk is based on an ancient Egyptian artifact called a DiaDhank, a golden device worn similarly to the Duel Disk that uses the user's Ba (life force) to summon Ka (spirit monsters) and control them. Unlike the Duel Disk, the DiaDhank can only control up to three monsters at once. In place of the Life Point counter is the The Eye of Wdjat, which contains a glowing yellow meter that measures the user's Ba, as the disk measures life points. Since summoning monsters drains life force, the losing duelist faints or dies. It is heavily implied only Millennium Item bearers can use a DiaDhank.

The design of the second Duel Disk suggests that Seto Kaiba designed it based on memories from his past life as Priest Seto, who used the Millennium Rod. The Academy Duel Disk also seems to take elements from the DiaDhank, as its shape when in standby mode looks like the blades on the DiaDhank. Yubel's dueling arm looks like a demonic version of the ancient device, as well.

Shimon Muran describes a DiaDhank as a device use for calling for Shadow Creatures that are sealed away in Stone Tablets.

DiaDhanks did not appear in the manga. Rather the priests used the power of their Millennium Items to summon the creatures from the stone tablets.

Duel Disk (Version 1)
Duel Disk 1During the Duelist Kingdom arc, Seto Kaiba developed the first generation duel disk prototypes as a means of countering Maximillion Pegasus' mind reading techniques. Seto gambled that Pegasus needed face to face contact for his mind reading to work so as a feature of the disks, holographic projections of the cards obstruct the duelists from seeing each other.

This duel disk was physically and functionally different than the ones that would follow. Where the others are a single piece construct which houses the Deck, Graveyard, Life Point counter and Field, the first Duel Disk system had two components joined by a retractable cable. The wrist component houses the Deck and Life Point counter, and the actual disk component holds five cards. Users would load the cards as explained later into the disk and throw it like a yo-yo, causing hologram to be projected from it.

The duel disk system also changed the rules of Duel Monsters. They followed Duelist Kingdom rules except for the following changes: An early variation of this system is used in Toei's [http://yugioh.wikia.com/wiki/Yu-Gi-Oh!_the_Movie Yu-Gi-Oh! movie].
 * Both players draw cards until they have 5 in their "hand". If they have 5 then can draw no more.
 * One monster card is placed on the "Main card stage", the centre place on the disk.
 * The other 4 cards are placed face down into the other places, the "Sub card stage".
 * The players can only attack with the monster in the main card stage, providing it is in attack position first. It can attack the opponent's main card stage monster or one of the sub stage cards.
 * Any monsters in the sub card stage are considered to be in attack position, and damage calculation is done accordingly. Spell and Trap Cards are destroyed with no calculation done.
 * The players may shuffle their sub card stages at their discretion.

Duel Disk (Version 2)
Duel Disk 2Prior to the Battle City Tournament, KaibaCorp developed the second generation Duel Disk, the first one to be released to the public. Issued to participants of Battle City, this Disk played the game according to the new revisions (which make it closer to the real world version.) Unlike the previous Duel Disk, it did not need to be thrown (In the Yu-Gi-Oh! anime, sealers flew out of the Duel Disk to the sides of the dueling area. These disappeared in Yu-Gi-Oh! GX). When in use, it resembled an arm blade. Monsters that are in play are placed on the five slots on the blade. Directly underneath each Monster slot is another slot for Spell and Trap Cards. If a Duelist were to activate a Set card, they would activate a button on the round portion of the disk. Another slot can open on the front end of the disk that is used for the Field Spell Card. The center of the Disk includes the Deck and Graveyard slot and Life Point counter. The bottom part of the disk (the part that goes around an user's arm) also contains a retractable cable that could be attached to Dueling Arenas if one player opted not to use a Duel Disk. Ever since their introduction, almost all duels were conducted with these, or with the later introduced Chaos Duel Disk.

In the manga both magic and trap cards were placed on the same slots for monsters, but in the anime this is improved by having a seperate set of slots for magic and traps under the duel disk. Also in the anime 2 holographic devices fly from the disk and set themselves on each side of the duel space to create the holograms for the monsters. While in the manga the holograms are projected straight from the duel disk itself.

In [http://yugioh.wikia.com/wiki/Yu-Gi-Oh!_5D%27s Yu-Gi-Oh! 5D's], This version of the Duel Disk is shown being used by citizens of Satellite, indicating that this model has become obsolete, replaced with the more modern versions shown in GX, as well as the D-Wheel and other Duel Disk versions that are shown. Also, the protagonist of 5D's, Yusei Fudo, is shown to remove a duel disk from his D-Wheel which has a startling resemblance to this version, possibly indicating that he has modified the obsolete model for use with his D-Wheel.

Despite other models of Duel Disks being used primarily in each series, this version of the Duel Disk has appeared in all three anime series, as shown with all the students who tried out for Duel Academy prior to receiving the Academy-issued Duel Disk and the residents of Satellite.

Mattel's Duel Disk 2The toy company Mattel produced replicas of this Duel Disk. There are a couple of notable differences between the Mattel Duel Disk and its fictional counterpart. The Spell and Trap Cards are loaded into the bottom of the blade, but most notably, it cannot project holographic images.

While the toy Duel Disk was advertised as being compatible with the TCG, there are a few flaws that make this impractical:
 * Most players used card protectors to prevent damage to their cards. Cards in protectors will not fit into the Duel Disk.
 * The Deck Zone can only hold about 50 to 59 cards safely. The Academy Duel Disk can hold 65 cards in total. While most players stick to the minimum, there are those who use bigger decks and cannot use the duel disk. Though, the new rules made a maximum of 60 cards making the limited holding capacity problem moot.
 * The graveyard can only hold about 20 cards. This would present a problem when playing against someone who relies on running an opponents deck out.
 * No place for Fusion Monsters or cards that have been removed from play. (This is also true in the anime, as any removed from play cards are often seen placed into the duelist's pockets
 * The Life Points counter can only go up to 9990 life points. While both players start with 8000, 4000, or 2000, it could rise to 9000 or 10,000+ Life Points due to card effects. The reason for the zero at the end is because while there are four buttons on the disk, only 3 of them change the counter, the last one lights up the display. This also serves the problem that some cards can cause the Life Points in the ones place to be a number different than zero.
 * The way the duel disk moves from stand-by to in use is also different. In the anime, the Graveyard is locked over the deck, and the two field parts are retracted into the main part of the disk. When triggered, the field parts and graveyard are unlocked, and the central piece rotates the graveyard and field into play position. The toy however does not have a rotating center, and the two halves of the field aren't locked in closer to the central piece. When the player triggers the toy into play mode, the smaller half of the field, which is spring loaded, is released from it's lock at the same time as the larger half which has a weaker spring, and thus, the smaller part pushes the larger part into play position.

Chaos Duel Disk
The standard Chaos Duel Disk

The large, bladed Disk of the Orichalcos SoldiersThe Chaos Duel Disk is a Duel Disk designed for the members of the organization called Doma in the Waking the Dragons arc. Functionally, it is identical to the Battle City duel disks except that, except for projecting holograms of monsters, it appears to cause the monsters to physically manifest. It looks different to the Battle City disk in that it resembles a scythed blade. It is believed to be modeled after the scythes on the armour of the Orichalcos Soldiers.

Mattel's Chaos Duel DiskLike the Duel Disk 2, The company Mattel manufactured replicas of the Chaos Duel Disk for use with the real TCG, however the same flaws in the Battle City disk. These include not being able to use card protectors, lack of a Extra deck zone and not being able to have more life points than 9990 even though a card effect such as "Solemn Wishes" can boost your Life Points beyond this. Therefore in order to calculate the user's Life Points if they exceed this the user must use some way to keep track such as a calculator. It also folds in different, instead of the front tip folding into the center, the monster zone closest to the field spell zone is visible. In the anime, the Chaos Duel Disk folded in on itself until the field was completely folded into the hinged 'spell trigger' part of the disk, and then folded into the central part of the disk, creating a compact form. The toy is much the same, but cannot fold all the way as the anime disk can, but instead leaves the first card space out. The hinge on the toy is the whole of the first and second card spaces, which pushes to the back of the central part, and though not as compact as the anime Chaos disk, it is still the most compact and light-weight of the toy duel disks.

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Academy Duel Disk
Academy Duel Disk, the 1st version

Academy Duel DiskA streamlined version of the second Duel Disk. This is the standard Duel Disk issued to students of the various Duel Academies established by Seto Kaiba in the [http://yugioh.wikia.com/wiki/Yu-Gi-Oh!_GX Yu-Gi-Oh! GX] series. Aside from the obligatory alternate folding feature, and a cosmetic refit, this Disk functions identically to the second Duel Disk. The shift from standby to active mode of this version of the Duel Disk is much less pronounced than the Battle City variant, only requiring the top section of the card platform to extend.

Mattel's Academy Duel DiskAs with the Duel Disk and Chaos Disk, the toy company Mattel made replicas of the Duel Academy Disk. They fixed one of the main problems of the Disks in resizing the card zones, along with deck and Graveyard to fit cards with protective sleeves without problems. Although this problem was addressed, many of the other problems remained. Though the main flaw with the Duel Disk was addressed in the new Academy Disk, many of the major flaws still remained unaddressed. Though the Duel Disks are perceived as "toys", few use the Academy Disk in place of taking up space on a table. Along with the release of the Academy Disk, Mattel produced a specialized carrying pack for the new disks, though none have been actually seen used or in stores. Due to past sales of the Academy Disk and the limited popularity with the toy as a dueling medium Mattel discontinued the production of the Academy Disk several months after its release.
 * No place for removed from play cards and the Fusion Deck.
 * Straps are one size only. This was a major problem for players who were bulky in the wrist region and used the Academy Disk in order to save space and not use a table or for fans who wished to use the disk as part of a cosplay outfit.
 * The Life Point counter is still limited to 9990.
 * Owners of the Academy Disk accounted that between different Academy Disk that there was a variance of 34 - 40 cards held within the deck zone.

Academy Duel Disk (Version 2)
The upgraded version, with Slifer Red colors.An updated version of the Academy Duel Disk which now has the color of the user's respective dorm on it. In season four, the duelists are using these new duel disks.

The upgraded version, with Slifer Red colors.*Academy Duel Disk (Version 2) - Slifer Red These Second Generation Academy Duel Disks are used by Slifer Red students.

The upgraded version, with Ra Yellow colors.*Academy Duel Disk (Version 2) - Ra Yellow These Second Generation Academy Duel Disks are used by Ra Yellow students.

The upgraded version, with Obelisk Blue colors.*Academy Duel Disk (Version 2) - Obelisk Blue These Second Generation Academy Duel Disks are used by Obelisk Blue students.

Many characters who no longer attend Duel Academy (such as Aster Phoenix) continue to use the silver style Academy Duel Disk. The change is cosmetic only and the Disks still retain the exact functionality of the original Academy Duel Disks.

In November 2007, a real-world version of the red-trimmed Slifer Red disk was also produced in Japan, known as Academy Duel Disk Osiris Red and came boxed with several booster packs and promotional cards.

Organic Disks
Several characters in Yu-Gi-Oh! GX have Duel Disks that seem to literally be part of their bodies, and are thus organic in nature.