Once upon a time, behind the tricorder’s upper door, to the left of the moiré disc, there was a row of eight curved aluminium features. Although their purpose was never made clear on screen, some tidbits of hearsay, extrapolation from scenes where Mr. Spock comes tantalisingly close to revealing their purpose, and an interpretation of that famous Wah Chang tricorder sketch, has led many fans, us amongst them, to conclude that these features were intended to be removable information or function-boosting discs.
Working on creating a replica of a 50-year-old science fiction prop is a bit like peering into the workings of a vintage time machine: the more you look, the more you learn about the past and how we see the future.
Since the invention of the gramophone in the 1880s, for more than a century, discs of one form or another were the predominant format for machine-readable information storage. As Star Trek was being brought to life, International Business Machines Corporation (IBM) was in the process of introducing read-write memory drives in the form of removable magnetic media discs. Eight discs high and 360 mm (14”) in diameter, and costing a cool quarter of a million dollars, the then-revolutionary IBM 2314 was able to store 233 MB of information. It is not unreasonable to conclude that Chang knew of IBM’s hi-tech data storage solution, and imagined a future where those monster discs would be reduced to thumb-sized drives that could quickly be swapped in and out of a handheld computer in order to augment its capability.
Right from our earliest tricorder development discussions, we felt it was our duty to do something special with the removable data disc concept, which we knew would add a level of immersive interaction and realism to our replica tricorder. Initial thoughts of creating plug-in data discs with USB flash drives buried in them were quickly ruled out. Not only are the discs very close together – requiring a push-to-release mechanism to access them – but we felt that a prosaic, and obviously 20th century, USB plug would look clumsily incongruous on a piece of 23rd century tech, especially when compared with the other uncluttered-looking memory cards clearly in use on the Enterprise.
Our first task was to design an ejector mechanism that would work smoothly and reliably, and fit in the limited space the prop has to offer in this area. The eight-disc array is fairly tightly boxed in between the hood, the lower compartment cavity wall and the back of the tricorder. Disc insertion and ejection is further complicated by the fact that the disc diameter is larger than the apparent opening the discs must pass through to be taken in and out of their dock. An array of spring-loaded latching switches attached to thin, crescent-shaped, bendy ‘catcher’s mitts’, which flex to hold and eject the discs, coupled with an upper “glamour bar” that rotates out of the way when a disc is ejected, provided the aesthetic functionality we were after. With all the discs inserted, and while being displayed in a cabinet, the glamour bar springs into position over the top of the array and the tricorder looks perfectly like a pristine version of the first season hero. But for those that want to boldly go beyond display and into the realm of realistic function, pressing any one of the discs ejects it with a satisfyingly premium click. The latching switch at the back of each disc slot tells the tricorder’s software which of the slots have discs in them.
With the ejector’s mechanical design well on the way to completion, we went to work on making the discs a plausibly functional part of the tricorder’s operation. Initially, we considered ways of ‘writing’ even just small amounts of data wirelessly to the discs (using an RFID chip embedded in the disc), but technical issues caused by the proximity of discs to each other, and the metal outer ring, closed down that idea. Given the capability of the tricorder’s internal electronics, and the onboard memory’s ability to cope with the functions we had planned for it, our thinking moved away from the complexity of adding hardware to each disc. To make the discs integral to the tricorder’s operation, for example, using them to activate the tricorder’s various functions, the tricorder has to be able to identify each disc. To simplify the identification process and add another level to the interaction required by the user to operate the tricorder, we chose to only monitor the disc slot furthest to the right. Using this as the activation position ties nicely in with the possibility that, in the hero prop’s original incarnation, this particular disc was the removable one. The right-most slot also allows us to hide the disc identification sensor behind the moiré panel.
To identify the discs, we chose colour sensing: it is human-readable, robust and reliable, and yet being non-obvious to the untrained user, appears suitably sci-fi. To add the necessary colour to the otherwise metal discs, in the absence of any hard evidence, once again Wah Chang’s sketch points the way. In it, what looks like a disc can be seen protruding from a socket next to the display. Although this particular feature never made it into the final design, the image shows what looks like a disc with a rim wrapped around a contrasting material. For the actual colours, The Original Series has a large and vibrant colour palette and there are plenty of richly coloured memory blocks and console switches which, between them, offer more than enough colours to provide an in-universe range of coloured disc inserts that an optical sensor can reliably differentiate between.
In use, inserting any of the discs into the right-most slot enables the user to access that particular disc’s set of related functions, information or files, and calls up any previously recorded data for those sensor functions. By using them in this way to control the tricorder, the discs become a properly engaging and integral part of the user interface, each one effectively acting as a specific data access key. The sensors, such as humidity, temperature and pressure, are interrelated so instead of assigning the function of a single sensor to each disc (and then leaving the other exciting tricorder functions buried in somewhere else in the user interface), we grouped the tricorder’s mix of dynamic and static information, capabilities and functions together more intuitively by usage.
Our tricorder does more than just sense and record data from the environment. Its capabilities will be explored in detail in future posts, but in broad terms, as a replica of a portable computer, it also has data banks that contain a catalogue of Captain’s Logs entries; access to the “status” of the Enterprise; information relating to its own internal status; statistics and useful data about the planets in our home solar system; and a small collection of historical archive files.
The tricorder is not just a replica of a measuring and recording device: it is a realistic incarnation of one of science fiction’s most heroic props and perhaps the earliest vision of a mobile computing future that we all now take for granted. At its heart, our tricorder replica isn’t a scientific instrument – in the round, it’s the embodiment of a shared dream that every Star Trek fan holds dear.
Coming next time
Moiré – The fringes of science
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