Minimum power for running RISC OS 5?

I wonder what the minimum power consumption is to run RISC OS 5? Which board has the lowest requirements? The Raspberry Pi zero? Can you reduce the power further by lowering cpu clocks? Will you be able to run RISC OS with – say – 100mW of power?

I think you’ll have to define what you mean by running RISC OS; just booting to the desktop and sitting idle, or performing a particular task?

Yes, the power can be reduced by lowering the cpu clocks. I have a 1B+ running 5.28 with 1 Watt power consumption.

Based on that, I would say that 100mW is too optimistic, even just sitting idle with no keyboard or mouse and, presumably, you want it to be doing something useful.

Pi Zero at 170mA with no USB items or monitor connected – that’s 850mW. Uses an OLED display for output and an ‘on’ and an ‘off’ button for input. Whilst shutdown consumes 100 micro Watts.

Do you need network?

With Ethernet, the best choices are probably the Pi2 and the Pi3B (or an underclocked B+).
https://www.pidramble.com/wiki/benchmarks/power-consumption

If you have other data… I’m interested. I plan to have a Pi for data sharing, Messenger and Organizer, with VNC client and DeskWatcher, and I would be pleased to get the lowest power connected Pi.

Do you need network?

If you do then the switch/hub/router is probably taking more power than the Pi (Unless you’re using a newer Pi at full throttle.)

I hunt every watt, everywhere.
Call it a fad :)