Collapse informatics is software engineering taking advantage of today's abundance in computing power to prepare for a future in which current infrastructures have collapsed.
It is based on decentralisation, not only because current centralised services and networks will break down, but also because peer-to-peer infrastructures are more resilient and flexible. It aims for simplicity, software should function on existing hardware and rely on modularity in order to enable a diversity of combinations and implementations.
Systems need to be resilient to intermittent energy supply and network connectivity. Collapse informatics prioritizes community needs and make use of open-source licenses to contribute to a knowledge commons in order to be able to succeed in case of economic collapse. The practice of engaging with the discarded with an eye to transforming what is exhausted and wasted into renewed resources.
A post-collapse society that has eventually lost all of its artificial computing capacity may still want to continue the practice of computer science in a purely theoretical level, as a form of mathematics.
Nothing new needs producing and no e-waste needs processing. If your new software no longer runs on old hardware, it is worse than the old software.