Last week, the IRISA lab in Rennes celebrated its 50th anniversary. For the occasion, the PACAP team was present to popularize its expertise, through two questions:
- How can we bring back to life a 50-year old computer?
- How can wireless sensors perform computations without battery?
Bringing an old computer back to life
Caroline Collange recently restored a Mitra 125 minicomputer from 1976, manufactured in the context of the “Plan Calcul“. This type of computer equipped the heart of telecom networks Cyclades and Minitel, was used to manage the power grid by EDF and was even used for Ariane IV space program.
This restoration work required a retro engineering of the whole micro-architecture, and to dive into Mitra microcode.
As of today, the system could be successfully programmed through its front panel switches. Ongoing work aims to make the associated 14-inch hard-drive functional again and resurrect the original operating system.
During the event, Caroline presented the Mitra story, how it was designed by engineer Alice Recoque as a side project, how it became popular in France and occasionally abroad, and how it works.
What if your wireless sensors didn’t need batteries anymore?
Matthieu Rodet and Hugo Reymond presented how battery-less sensors can work despite several power failures.
Wireless sensors are essential to gather data in remote locations. Unfortunately, regularly replacing their batteries is costly, has an important ecological footprint, and might perturb the surroundings.
To avoid this, an alternative is to use battery-less sensors, that are powered with ambient energy (for example, with solar panels). Powering sensors this way, while durable, makes the sensor prone to frequent power failures, as the energy available is scarce and unpredictable.
Thus, one question remains: how can we reliably execute programs on such devices?
To answer this question, Matthieu and Hugo presented a prototype of battery-less sensor, powered with solar energy. Through this prototype, they introduced how saving regularly the program state – aka checkpointing – allows to complete program execution. Moreover, they presented and illustrated how several parameters can impact a battery-less sensor execution : checkpointing frequency, capacitor size, amount of energy harvested…
The poster of this demonstration is available in French here.
Acknowledgements
This work has received a French government support granted through NOP Project (ANR-10-LABX-07-01) and OWL Project (ANR-23-IAS3-0003)
