When you say "sips power", what exactly do you mean?

I've been watching for an SBC you could use to make something like a TRS-80 Model 100. They ran off 4-AA batteries and would get you 20 hours of continuous use. That translated to at least a week of real world use (you wouldn't want to be typing on one for 4 hours a day...)

That was in 1983. Today, it seems like you should be able to make something similar that will run for weeks or months on AA batteries.

I don't think AA batteries have improved a whole lot over the past 40 years, but power requirements have definitely gone up. The linked SBC needs a 12v/2A power supply minimum. I think the CPU in the Model 100 used something like 1 watt max and even then I recall reading somewhere that it went as far as suspending clock cycles in between key strokes to conserve energy (this may have been something else, I can't find where I read it).

So in my very-much-not-an-expert opinion, I don't think it would be feasible to run a modern computer off of AA batteries, let alone for weeks.

The minimum power supply is dimensioned to allow for USB powered peripherals.

The idle power consumption of such a SBC like Radxa X4 must be significantly below 5 W, probably around 2 to 3 W.

That is still too high for standard AA batteries, but rechargeable batteries should work.

If a long battery life would be needed, it is likely that one can shut down the N100 CPU and wake it up either periodically or on USB activity caused by the RP2040 MCU. That should reduce the average power consumption to fractions of a watt.

To run on AA batteries you'd probably have to go to microcontrollers like ESP32 which are way less powerful than that Intel device but also way more powerful than TRS-80. Assuming a power consumption of 0.25W for that SoC and basic 2000mAh AA batteries, a 4 AA battery setup could run the device for 48 hours.

There are 300mW class Linux-capable chips like SAMA5D27. 500Mhz Arm Cortex-A5.

There are all kinds of Linux Capable chips available between 0.3W to 5W, and with LPDDR1 or other older standards, you can get very good and cheap prices while still only sipping power.

My n100 system idles at 10W from the wall. It has many more components to power (2x m.2, sata, 5x nics, etc.) than this SBC though.

Much higher than a raspberry pi, but still low in comparison to any desktop server

That is quite high for an N100 system, even if it is not uncommon and much of the power may be used by the listed peripherals.

Most well designed N100 systems that have only a moderate number of peripherals have an idle power consumption under 5 W.

10W? I think that means 4 AA batteries would keep it running for about an hour.

Does it have to be an SBC?

A modern MCU will absolutely run circles around the processing and memory capabilities of the Model 100, and can probably even do that for 20 hours using four AA batteries.

There a lot of applications for which a MCU is sufficient and it will be much cheaper and it will have a much lower power consumption.

However not even the fastest existing MCUs, i.e. those with Cortex-M85 cores, can reach processing or memory speeds comparable with CPUs like the Intel Alder Lake N series or the Arm CPUs using Cortex-A78 or Cortex-A76 cores.

The fastest MCUs may have a clock frequency of up to 1 GHz, but most of them have clock frequencies many times lower (this is because the MCU cores use shorter pipelines), while the SBCs use clock frequencies between 2 and 4 GHz.

The Cortex-M7 or Cortex-M85 MCU cores have an IPC (instructions per clock cycle) that is 2 to 3 times higher than the IPC of most other MCU cores, but even their IPC is 2 to 3 times lower than of Alder Lake N, Cortex-A78 or Cortex-A76. Due to the much higher clock frequency and IPC, the SBCs are much faster than any MCU.

Due to the MCU clock frequencies being under 1 GHz, not even their cache memories can have throughputs as high as the DDR memories of the SBCs, which use 4.267 to 4.8 giga transfers per second.

So any modern SBC will run circles "around the processing and memory capabilities" of any MCU. However, you are right that in many cases the speed of a SBC is not needed and a MCU is good enough.

A SBC is typically needed when you want a USB 3 interface or an SSD, because extremely few MCUs have any peripheral interface faster than 1 Gb/s Ethernet.

Correct.

But in context: It simply can't take very much grunt to provide a modern take on a ridiculously-limited portable computer from 1983.

The TRS-80 Model 100 that is the context here had an 80C85 processor running at a scalding 2.4MHz, and featured as much as 24 kilobytes of SRAM.

And that's a pretty excellent spec for a portable computer in 1983, but it's a complete snoozefest compared to a RP2040 dev kit like the Pi Pico (at a cost of around three US dollars).

RP2040 is just a microcontroller vs the "full computer" of a normal pi board. This is the distinction people are usually making when they say RP2040 isn't a pi.

This board is a full intel computer plus a rp2040 driving the pi-style GPIO pins. It should basically be able to do whatever a pi can do.

To be compatible and be able to use all the Pi Hats would be nice but my point is that I am not sure a RP2040 can replace the Pi and be called "compatible". You can do a lot with an MC on the board that is true.

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