Just what it says. A 4 GB Rπ costs £8.63/month ≈ €9.57/month.

Highly optimised minimal Debian OS

DietPi is extremely lightweight at its core, our images start at 400MB in size (3x lighter than 'Raspbian Lite'). With features of low process/memory footprint and DietPi-RAMlog installed by default, DietPi allows you to get the maximum performance from your device.

Brief description of a failed attempt to install the virtual AGC
from https://www.ibiblio.org/apollo/ on a Raspberry π 4 running Raspian.

Probably using the Spigot Algorithm from Stanley Rabinowitz.

How to install FreeBSD/ARM on computers of the Raspberry Pi family.

Collection of articles describing various applications for the Raspberry π (in german).

The entire desire to do this came about from reading about building a Stratum 1 clock using a Raspberry PI at http://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html and from the use of a Sony radio clock to provide WWVB pulses from the WWVB receiver module that was used in the radio clock.

However, all of the projects and examples I found used Linux which I did not really want to use. I much preferred to use NetBSD, but it lacked a number of critical features that would be required to make a properly working Stratum 1 clock. Interrupt support for the GPIO pins was needed and adding a PPSAPI driver that could be triggered by a GPIO interrupt would be necessary.

The Cosmic Pi project aims to build the world's largest open source distributed cosmic ray telescope. You can be a part of the project, by becoming a Cosmic Pixel!