# TRL4 - Breadboard version in lab This is the first time that you assemble all the components of the eventual final system. You need to have at least a simulacra of every piece of the real system. The ‘lab’ part of the description means that every simulacra component of the real system is under your control. The ‘breadboard’ part of the description means that the interfaces between the components can both be hacky (maybe it’s just someone copying over a text file) and completely instrumented - the analogy is that in a breadboard interface you can easily put alligator clips and measure any interface. Perhaps it suggest an imperative for software at TRL4 - to put digital alligator clips on different interfaces. Taking a credit card fraud detection algorithm as an example, you need to have at least a simulacra of every par of the customer facing piece, etc. In health focused biotech, the ‘lab’ would be cells in a Petri dish. <!-- #evergreen --> [Web URL for this note](http://notes.benjaminreinhardt.com/TRL4+-+Breadboard+version+in+lab) [Comment on this note](http://via.hypothes.is/http://notes.benjaminreinhardt.com/TRL4+-+Breadboard+version+in+lab)