|Spoiler Alert: This page contains spoilers. Read at your own risk.|
Casting Assistant Device (術式補助演算機), better known as CAD (シーエーディー) is a spell support processor. Magicians also call them Device (デバイス) or Assistance (アシスタンス), and in Japan Magic Operator. It is a machine researched & developed using Magical Engineering Technology.
Use & Working
This device incorporates synthetic materials (artificially manufactured Neurons) that convert Psion signals into electric signals, using the Psion from a magic ritual (sequence) to produce a collection of electronic magic — the Activation Sequence.
CADs allows the processing of all the necessary components for magic in a single moment. In detail, these devices help accelerate the invocation of magic, as well as provide stability.
CADs replace traditional tools such as spell chants, talismans, magic staves, tomes, hand seals, magic circles, and other traditional methods of invoking magic. It is a tool of necessity for any modern Magic Technician.
- If a magician "A" places hands on a magician "B"'s CAD while the magic is being cast, then magician "A" will receive the interference 1000 fold (times). 
Development, Production & Sale The development, production and sale of CADs are heavily subsidized by the government as a matter of national interest. Retail pricing is only 10% of the actual cost, as a result of that policy. Even so, families can usually only afford to purchase one CAD per child as a celebratory present when they enter high school. Turnover sales are low since a magician might personally own only 5 or 6 CADs and there are only about 30,000 CAD users of high school age or older. These factors make the civilian CAD market a difficult one and cause companies to be heavily beholden to their respective governments.
At the heart of the CAD's is the induction stone. Induction stones are a component meant to connect psion signals and electrical signals. However, not all Induction Stones are the same and have to be adjusted depending on the design and efficiency. The designs of the stones are a significant intellectual asset of each company and nation.
There are CADs in different shapes or forms such as bracelet-shaped CADs, mobile terminal-shaped CADs, long and short gun-shaped CADs, rifle-shaped ones, and special weapons or ornaments that conceal a CAD like Erika's baton and Azusa's pendant.
Requirements & Usage
While it is a tool that helps with magic invocation, it does not mean that anyone who possesses a CAD can use magic. The CAD only provides the activation sequence, and it is the ability of the Magic Technician himself that invokes the magic.
Magicians infuse Psion particles inherent in their bodies into the activation sequence output by the CAD, and feed that from the subconscious magic processing system present in all magicians into the magic operations area. Here the activation sequence is expanded, and all the necessary parameters input, in order to assemble the magic ritual.
Types of CAD
- These are CADs which could store up to ninety-nine types of Activation Sequences without regard to the systems of magic, but place a larger burden on the user. These CADs have the advantage in versatility and are often used by magicians who can wield different types of magic.
- Nine Schools Competition
- Main Article: Air Mine
- During the Speed Shooting event where Shizuku competed, Tatsuya was able to incorporate auxiliary sighting systems (auxiliary aiming device) into a general-purpose CAD, a feature usually only possible when using a Specialized one. It was also noted by Mikihiko that he has never seen a rifle-shaped general purpose CAD until that event.
- Main Article: Air Mine
- It was mentioned that a prototype incorporating auxiliary aiming device on Generalized CAD was unveiled in Dusseldorf, Germany the summer before, but was cast aside because the operation was sluggish and the accuracy was low, rendering the experiment a failure.
An example of a Generalized CAD made by Four Leaves Technology (FLT):
➨ Centaur Series
- It is a type of general-purpose CAD which doesn't have any interfaces on the main body and can be used without any external input devices. The connector, however, has a grip and auxiliary aim assist system attached.
- Related Article: Taurus Silver
|"Silver Series Custom Silver Horn", a Specialized CAD optimized for Loop Cast.|
Although this type of CAD has the advantage with speed (over Generalized ones), the number of activation sequences that can be used is limited. Specialized CADs can only store nine types of Activation Sequences of a single system of magic, and is originally intended for Magicians who are strong in select/specific type of Magic (from the 4-Systems & 8-Major Types).
The Specialized CADs are often shaped in the form of guns as they have the auxiliary aiming systems incorporated in the area corresponding to the barrel. Co-ordinate data is input at the moment the activation sequence initiates, in order to reduce the calculation load on the user. Psions aren't emitted from the muzzle. 
Specialized CADs can also be found in other forms as well.
- For example:
- Chiba Erika's Baton-type CAD (the baton is completely hollow except for the handle, it uses Engravement Magic, with geometric patterns & seals engraved onto a sensitive alloy which activates when Psions are injected.
- Saijou Leonhard's Glove-shaped CAD (the CAD is actually inside & protected by the gloves covering it).
- Tomitsuka Hagane's Gloves-shaped buttons connected to the Specialised CAD on the wrist.
|“||On the other hand, Tomitsuka wore the uniform for the Magic Martial Arts Club. The top half contained a long tunic without buttons that had padding around the forearms while the bottom half had pads around the knees as well as loose pants that only tightened around the ankles. On his feet, he wore soft sneakers used during fighting competitions. With protective gloves over both hands, all 8 fingers besides the two thumbs were wearing thick rings that served as the Specialized CAD input devices for the Magic Martial Arts Club. Each ring corresponded to one button and when the fingers moved (pressed by the thumb) or Psions gathered around his fingertips, the signal for the Activation Sequence selected by his fingertips would be passed through the glove to the connecting CAD around his wrist. In other words, Tomitsuka had prepared himself very seriously.||”|
—- CAD Description from Volume 12, Chapter 16 Page 326
A few examples of Specialized CADs:
- Silver Series (developed by Four Leaves Technology - FLT)
- Silver Series Custom Silver Horn (FLT)
- Silver Series Custom Trident (FLT)
- Silver Series Flight Assistance Device (FLT)
- Sagittarius Series (FLT) 
- Maximilian Speed Shooter 
- Russ Type-F 
Also called Thought-operated CAD
Although not a separate category in itself, it is worth to mention these devices. Rosen Magicraft was the first manufacturer to produce thought-controlled CADs. Their solution is based on "incorporating an exclusive mechanism utilizing a Psion wave-activated switch, which, as a device, would enter a fairly large size."
The second to market this is Four Leaves Technology with their product. Their device is "one solely specialized to produce the Activation Sequence for Non-Systematic Magic operating the CAD. Where traditional CAD focused on producing given Activation Sequences for designated magic through finger input, this device realized that through Non-Systematic Magic input." However, the FTL one is not a standalone product, it "mandated installation of a pairing software that coupled to the CAD". "The pairing software covered eighty percent of the CADs that had been put on the market in the last five years, regardless of whether they were general purpose or specialized models. Because it could be manipulated by Psion waves alone, this new product was expected to triumph over the issue of brand designs and generate large demand as a supplementary product."  FLT’s devices, unlike Rosen’s devices use two devices in conjunction with each other. While this may seem to be an inconvenience to use two devices, it also means that you don’t have to use your hands at all to manipulate the CAD which Lina mentioned is the trouble of manipulating a CAD is a hindrance for magicians who engage in hand-to-hand combat. 
Tatsuya uses/used the prototype of fully thought-operated CAD (bracelet shaped) "Silver Torus" instead of Silver Horn Specialized CAD (Torus meant ring rather than Taurus)
Tatsuya also gives Lina another Thought-controlled CAD in a form of a gold choker with a silver bracelet. Lina mentions that the USNA had tried to make their own version, but nothing has come to fruition yet. This was surprising to Tatsuya, considering the USNA had a scientist capable of making the Brionac. Tatsuya didn’t know their name but their technical ability was unquestionable because he had seen Brionac in person. 
This is a type of CAD that takes the form of a weapon (e.g. Sword) or weapons that conceal a CAD. The utility is even more restricted than a Specialized CAD and could only provide one Activation Sequence. Magic written into the Weaponized-Integrated CAD usually involved buffing its martial ability — the "weapon's" ability. "Blades" usually improved cutting power. "Spears" buffed their piercing force. "Rods" strengthened their striking power. "Shields" empowered their defensive abilities.
- Monolith Code
- Example: Mini-Communicator, was used by Saijou Leonhart during the Nine Schools Competition in 2095.
Notice: The Stars standard issue combat knives equipped with Molecular Divider magic and the automatic pistol of Angie Sirius equipped with Data Fortification magic carry the signatures of Weaponized-Integrated CADs, although them being WICs is not confirmed yet.
Sorcery Boosters by No Head Dragon. Some times it is also referred to as Magic Amplifiers. But they do not amplify in the classical sense. This device is a CAD that possess a self-restoring blueprint built into the Magic Sequence that assists in the construction process. Through this, Magic Sequences of large scale are rendered possible by surpassing a Magician's original capacity. Hence, it can also be called as a "Memory Capacitor". No Head Dragon is one of the primary distributors of this Booster, although they are later said to have monopolized the supply for Sorcery Boosters.
|“||Induction Stone refers to the component that transforms Psion waves into electric signals and vice versa. Induction Stones are created from a crystallization of neurons chemically synthesized from the molecular level. Since the differences in structure may impact the conversion ratio, the emphasis is placed on the structural composition rather than the physical characteristics of the neurons. That being said, currently there are no reports of successful developments of Induction Stones without relying on artificial materials.||”|
The core of the Boosters are not formed from artificial neurons but is made of a Magician's Brain 
Charms, Sutras, Talismans, etc.
In Volume 9 (Chapter 6), Mikihiko used a supplemental CAD based on Tatsuya’s suggestions and his own ideas (designed to streamline Ancient Magic that utilizes both Incantations and Talismans). It is a fan like object made of metal strips that have engraving of various incantations and formations (favored by practitioners, iron strips forms a conduit for Psions) connected to another device inside his sleeve that has activation sequences (replacing any need for incantation)
Although CADs show the superiority of modern magic, as it is a precise piece of machinery it requires regular maintenance involving the tuning of the machine to suit the traits of the user's Psion waves. This is especially the case when dealing with the compatibility between the user's Psion Wave Motions and the Receive-Release System. In this aspect, it is less useful than traditional mediums used in ancient magic. This makes it a requirement for the hardware and software of the CAD to be customized according to the user and its usage.
CADs use Psions released by magicians as raw materials directed towards the Activation Sequence in the Psion Information Aide, where Magicians then use their own physical bodies as a conductor for reading the Activation Sequence before plugging the result into the magic design. Psions are thought particles or consciousness made concrete and their manifestations are diverse. For 100 people there would be a 100 different types, as every individual has a unique Psion Wave Motion, so if the CAD wasn't finely tuned to their specifications, the user would encounter difficulty managing the exchange of Psions.
In addition, the fluctuations of Psion wave motions reflect the growth of physical body, such as changes as a result of age, which may result in daily changes.