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Comment by initramfs | Hacker News Reader

Hello, I am interested in your research as well as MicroMagics. The Claremont (32nm Pentium) and MicroMagic are the only application processors that have utilized NTV by stabilizing the voltage at 350mV-500mV. I started a project to make solar powerable mobile devices https://hackaday.io/project/177716-the-open-source-autarkic-... My email is available in the github's linked.

There are other processors, such as Ambiq Micro, but they are Cortex M4 and M55: https://www.top-electronics.com/en/apollo510-soc-250mhz-3-75...

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We've designed $0,10 ultra low power 8/16/32/64 bit processor SoC with built in MPPT buck/boost converters so they can be powered directly from single solar cells or small charge Li-ion cells. They have low power networking so you can create clusters. I'm not sure yet if they will be even lower power than you 5 mW processors but 1 mW is our aim.

I would argue that a solar powered computer would benefit from a 2 megabyte (could be as low as 128KB) SRAM operating system with GUI like Squeak or Smalltalk-80 instead of a Linux as you propose. We've learned a lot from the low power OLPC designs.

Thanks for the invite, I'm eager to collaborate on your solar powered computers but I'm having trouble finding your email in your githubs. Could you email us morphle73 at g mail dot com?

Thanks, it is giovanni dot los___ at gmail.com (it should be in your inbox)

Also, Ambiq Micro has a 2MB MRAM (+2.75MB SRAM) processor https://www.top-electronics.com/en/apollo4-blue-plus-192-mhz... that can run on solar power (it uses ~5uA/MHz, Cortex M4) and Andreas Eriksen got LISP text editor to run on 384K RAM with the Apollo3 https://hackaday.io/project/184340-potatop and 4'4" Memory In Pixel Display.

I read that lithium-ion capacitors have much faster charging than regular li-on. https://www.tindie.com/products/jaspersikken/solar-harvestin... (and longer lifespan)

That sounds very suitable for solar powered IoT and IIoT sensors, so the talk about GUI's feels confusing. Zephyr or freertos are perfectly fine with sub-2meg amounts if SRAM.

this is pretty exciting! i agree about the squeak-like approach. what would you use for the screen? i've been thinking that sharp's memory-in-pixel displays are the best option, but my power budget for the zorzpad is a milliwatt including screen, flash, and keyboard, not just the soc

There are ultra low power ePaper displays that only need power to change pixels but need no power to light the display or hold an image. They are usually black and white or grayscale.

> Typically, the energy required for a full switch on an E-Ink display is about 7 to 8mJ/cm2.

>The most common eInk screen takes 750 - 1800 mW during an active update

The Smalltalk-80 Alto, the Lisa and the 128K Mac had full window GUIs in black and white and desk top publishing.

The One Laptop Per Child (OLPC) had low power LCD color screens especially made for use in sunlight and would combine nicely with solar panels.

hey, i've been looking for those numbers for years! where did you get them?

the particular memory lcd i have is 35mm × 58mm, which is 20cm², so at 7½ millijoules per square cm, updating the same area of epaper would require 150 millijoules to update if it were epaper. the lcd in fact requires 50 microwatts to maintain the display. so, if it updates more than once every 50 minutes, it will use less power than the epaper display, by your numbers. (my previous estimate was 20 minutes, based on much less precise numbers.) at one frame per second it would use about a thousand times less power than epaper

so in this context epaper is ultra high power rather than ultra low power. and the olpc pixel qi lcds, excellent as they are, are even more power-hungry

pixel qi and epaper both have the advantage over the memory lcd that they support grayscale (and pixel qi supports color when the backlight is on)

>hey, i've been looking for those numbers for years! where did you get them?

I just googled "low power epaper" and read the summaries for mentions of mW and J

can you link to the sources that those numbers came from? i wouldn't be surprised if serp summaries were llm-generated nonsense

like, when i search for that phrase i get a lot of pages like https://www.marctech2.com/news/e-paper-faq-and-applications which is obviously llm-generated bullshit, some pages like https://goodereader.com/blog/e-paper/swedish-startup-rdot-is... with a conflicting number of 4 millijoules per square centimeter, and no links to actual sources who took measurements

what's ntv?

NTV = Near Threshold Voltage

https://www.anandtech.com/show/5555/intel-at-isscc-12-more-r...

>At IDF last year Intel's Justin Rattner demonstrated a 32nm test chip based on Intel's original Pentium architecture that could operate near its threshold voltage. The power consumption of the test chip was so low that the demo was powered by a small solar panel. A transistor's threshold voltage is the minimum voltage applied to the gate for current to flow. The logical on state is typically mapped to a voltage much higher than the threshold voltage to ensure reliable and predictable operation. The non-linear relationship between power and voltage makes operating at lower voltages, especially those near the threshold very interesting.

aha, thanks! the description of the threshold voltage in the text is wrong though; it would imply ambiq’s product wouldn't work at all

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