A quad is a measurement of information in Federation computers. While Federation computers still use binary code in some capacity, they also are known to use trinary code.
Measurement table
The values of various amounts of quads can be expressed as kiloquads, megaquads, gigaquads, teraquads, petaquads or exaquads, depending on the order of magnitude of the data being expressed.
Kiloquad
- William T. Riker used some computer jargon to confuse a Ferengi attempting to hijack the USS Enterprise-D's control functions. Among the other made-up references, he mentioned 14 kiloquad processors. (TNG: "Rascals")
- In 2374, when USS Voyager made contact with Starfleet Command after years alone in the Delta Quadrant, they transmitted hundreds of kiloquads of data home about the region they had traversed. (VOY: "Message in a Bottle") Of that, Arturis was able to reconstruct over 68 kiloquads of information, however, much of it was still garbled. (VOY: "Hope and Fear")
- Reginald Barclay described being transported as being converted into billions of kiloquads of data. (TNG: "Realm of Fear")
Gigaquad
- After Chakotay's bioneural energy was restored to his corporeal body, the Doctor mentioned that the procedure responsible involved "three neural transceivers, two cortical stimulators, and fifty gigaquads of computer memory." (VOY: "Cathexis")
- The Emergency Medical Holographic Program Mark I took up 50 million gigaquads of computer memory, noting that that was "considerably more than most highly developed humanoid brains." (VOY: "Lifesigns")
- The Doctor had accumulated 15 thousand gigaquads of unnecessary information in his holomatrix, including opera and romantic relationships (VOY: "The Swarm")
- After the warp ten test flight by Tom Paris on the Cochrane, the sensor logs of the shuttle collected nearly five billion gigaquads of information. (VOY: "Threshold")
- Seven of Nine collected over 30 thousand gigaquads of research about romantic relationships. (VOY: "Someone to Watch Over Me")
- After a long ordeal while in contact with a being known only as "the distortion ring" B'Elanna noted that they had over twenty million gigaquads of new information input into the ship's computer. (VOY: "Twisted")
Teraquad
- The crew collected 60 teraquads of data about the graviton ellipse. (VOY: "One Small Step")
- The Doctor's matrix became destabilized after he assimilated more than 1000 teraquads of data. Seven of Nine and B'Elanna Torres averted his decompilation by purging his excess subroutines. (VOY: "Renaissance Man")
- Seven of Nine analyzed 30 million teraquads of data to support a conspiracy theory after being driven to paranoia by an influx of information. (VOY: "The Voyager Conspiracy")
- The futuristic Borg drone named One was hungry for information – he assimilated 47 billion teraquads of information upon maturation. (VOY: "Drone")
- Additional references
Background
This terminology was originally developed by technical advisers to The Next Generation. The unit of measurement originated in the Star Trek: The Next Generation Technical Manual, and was also used in the Star Trek: Deep Space Nine Technical Manual.
The terms quads and kiloquads in TNG were used in a manner consistent with the system defined in the Technical Manual. However, by the time Voyager was airing, they started using extremely large numbers that lacked internal consistency, such as "billions of gigaquads" and "billions of teraquads." If these are accurate, USS Voyager's computers are more advanced and have a capacity that is orders of magnitude greater than the ones just seven years earlier in TNG.
Writers and advisers deliberately used prefixes used with bytes in modern day notation (mirroring kilobyte, megabyte, gigabyte, and terabyte). The terminology "quad" was used to detract from comparisons possible with modern-day computing power, since reality frequently outstrips fiction when it comes to computer science. Current capabilities are orders of magnitude greater than what scientists expected them to be only 20-30 years ago.
Given this exponential increase in computer capacity, and extrapolating it forward by three and a half centuries from the present, it may be that "quad" is meant to be an abbreviation for "quadrillion", as in 1015 bytes or bits--what we would call a petabyte/petabit, or one thousand terabytes/terabits, an amount that desktop computers should be able to store in their hard drives (or equivalent) by the year 2020. Given also that usage of prefixes larger than tera (peta, exa, zetta, yotta) are sufficiently unfamiliar to many viewers as to require explanation, there was a clear need for some method of expressing data with a larger unit than terabytes.
From the terminology, a kiloquad is perhaps one thousand (103), a gigaquad one billion (109), and a teraquad one trillion (1012) quads. Colloquially, the modern term kilobyte is usually used to refer to 1,024 (210) bytes, megabyte to 1,048,576 (220) bytes, and gigabyte to either 1,000 megabytes (103 * 220 bytes) or 1,024 megabytes (230 bytes). Because of this confusion, the International Electrotechnical Commission introduced the prefixes kibi-, mebi-, gibi- (et cetera) to refer to powers of two; under this system, the technical name for 210 bytes is a kibibyte, and 240 bytes is a tebibyte.