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Sunlight-powered computing is an idea that is very, very ripe for arrival. It needs to happen. I sincerely hope we see, within a few years from now, e-ink lap

Sunlight-powered computing is an idea that is very, very ripe for arrival. It needs to happen. I sincerely hope we see, within a few years from now, e-ink laptops where one side of the screen and the underneath surface of the laptop consist of solar cells, and all one need do for a daily/weekly charge, is tilt the laptop in teepee orientation and let it charge, charge, charge. I've already decided personally to get off the grid as soon as possible - in my case, in the form of a sailboat outfitted with as much solar panels as possible. Having a solar powered laptop has been a fantastic dream for decades - I really think it's going to happen, commercially and successfully, within the next few years. I could already power my iPad and uConsole with portable solar and battery banks. This all just needs to get integrated, and someone is going to have a HUGE HIT on their hands ..

kragen 1y ago
I want that too, but it is much easier if you accept a significant loss in either computational capabilities or portability. A typical cellphone uses about 4 watts, and a laptop closer to 12, the difference mostly being the screen. If you use batteries and want to run the computer for half an hour for every hour it spends in the sun, you'd need at least two watts of solar panels. Mainstream solar panels are about 220W/m², so you need roughly 100cm² of panels (0.01m²), more if you don't tilt the laptop perfectly. The cellphone I'm typing this on is 82mm×165mm = 135cm², so you would have to devote ¾ of its surface to solar panels, not leaving much room for a screen. If you covered the back with solar panels instead, you could use it a third of the time if you left it face down in the sun to recharge the rest of the time. That's almost usable, but not quite. But, if you can cut the power budget by about an order of magnitude to about 0.4 watts, you can get to continuous usage with only a fraction of the face of the device devoted to solar panels. LCDs without backlights can help here, especially important for larger devices, but using lower-power CPUs is also important. You can see some of my previous notes on the topic, listing nanojoules per instruction for processors then available, at https://dercuano.github.io/notes/keyboard-powered-computers.html#addtoc_4 https://dercuano.github.io/notes/keyboard-powered-computers..... Ambiq's subthreshold microcontrollers go much lower. Much of my own interest in this is because batteries and charging are almost always what breaks on computers these days, so I'd like to be able to get by entirely without batteries, just using solar panels, like a solar calculator. http://canonical.org/~kragen/sw/zorzpad.git/ http://canonical.org/~kragen/sw/zorzpad.git/ has some preliminary research into that.
- MomsAVoxell 1y ago
  Thanks for sharing your awesome notes.. I will devour these eagerly and learn from your journey so far. I don't mind lower power if it means I can get off the grid, and especially if I can have a small fleet of devices for the purpose of.. I'm already doing myself of my development work on the uConsole - it's not a fast PC, nor a beast in any sense, but it does function just fine for my use case. I could see an ARM64 cluster being solar powered with workable results. I agree .. the idea of a battery-less solar calculator-type computer would be grand. Lets see how long it takes for someone to design a viable product around this idea ..
  - kragen 1y ago
    There are a lot of levels of "not a fast PC", though. My power budget for the Zorzpad is one milliwatt, at which I think the Ambiq Apollo3 (an ARM Cortex-M4F) can deliver 20 MIPS, roughly equivalent to a Pentium-100 or a SPARC 5. It has 384KiB of RAM. The uConsole (https://www.clockworkpi.com/uconsole https://www.clockworkpi.com/uconsole ?) has at a minimum a 64-bit 1GHz RISC-V processor, on the order of 800 MIPS, 40 times as fast. Ambiq doesn't make ARM64 hardware. My theory here (and maybe this is just the inflexibility of old age, treating my own experiences as gospel) is that there's a kind of phase transition in personal computers along the path between, say, a PDP-8 or an Altair, and a SPARC 1 or a 486: ‣ PDP-8 or Altair (≈0.01 MIPS, ≈0.01 MB RAM): self-hosted development is almost impossible; you need a big computer like a PDP-10 to compile the operating system, although the small computer is capable enough to run an assembler, a BASIC interpreter, and non-optimizing compilers for languages like Fortran. Applications like word processing and spreadsheets can be sort of approximated. ‣ IBM PC, Apple //GS, or PDP-11/70 (≈0.1 MIPS, ≈0.1 MB RAM): self-hosted development is comfortable and responsive in languages like C or Pascal. Viable applications include things like 2-D mechanical CAD, word processing, version control, and spreadsheets. GUIs are clunky because redrawing the entire low-resolution screen takes a second or so. ‣ Macintosh 512K, Sun 3/60, 80486 (≈1 MIPS, ≈1 MB RAM): mouse-driven GUIs have reached basically the same form we use them in today on the desktop. Self-hosted development is the only way to go, and higher-level languages like PostScript, Emacs Lisp, Tcl, HyperTalk, Visual Basic, and Perl are popular. Viable applications include things like VLSI simulation, 3-D modeling, and Web browsers. So somewhere in that range there's a phase transition between "basically a peripheral of a larger computer" and "GUI workstation". The Apollo3, being a microcontroller, is balanced like a microcontroller rather than a personal computer: 100 MIPS (with FPU), but only 0.4 MB RAM. So it has the RAM of an Amiga 500 or a Mac 512, but the CPU speed of a SPARC 5, a Pentium 60, or a PowerMac 8100. (See https://netlib.org/performance/html/dhrystone.data.col0.html https://netlib.org/performance/html/dhrystone.data.col0.html.) My speculation is that, coupled with the much faster mass storage speeds available with NAND Flash, this ought to be enough for a comfortable self-hosted development experience. I mean, I wrote GUI apps and browsed the Web on a SPARC 5 and a 5x86-133. I suspect that the structure of the system software will have to be significantly different. (See https://rossumblog.com/ https://rossumblog.com/ for some examples of what people have done with small microcontrollers that are capable of running on low power.) But the uConsole will still be on the order of 10 times faster, and consequently (if we hold the underlying implementation technology constant) dissipate on the order of 10 times as much energy. Considering that it's using conventional CMOS instead of Ambiq's subthreshold process, the ratio is probably closer to 50:1.

kragen 1y ago

I want that too, but it is much easier if you accept a significant loss in either computational capabilities or portability. A typical cellphone uses about 4 watts, and a laptop closer to 12, the difference mostly being the screen. If you use batteries and want to run the computer for half an hour for every hour it spends in the sun, you'd need at least two watts of solar panels. Mainstream solar panels are about 220W/m², so you need roughly 100cm² of panels (0.01m²), more if you don't tilt the laptop perfectly. The cellphone I'm typing this on is 82mm×165mm = 135cm², so you would have to devote ¾ of its surface to solar panels, not leaving much room for a screen. If you covered the back with solar panels instead, you could use it a third of the time if you left it face down in the sun to recharge the rest of the time. That's almost usable, but not quite. But, if you can cut the power budget by about an order of magnitude to about 0.4 watts, you can get to continuous usage with only a fraction of the face of the device devoted to solar panels. LCDs without backlights can help here, especially important for larger devices, but using lower-power CPUs is also important. You can see some of my previous notes on the topic, listing nanojoules per instruction for processors then available, at https://dercuano.github.io/notes/keyboard-powered-computers.html#addtoc_4 https://dercuano.github.io/notes/keyboard-powered-computers..... Ambiq's subthreshold microcontrollers go much lower. Much of my own interest in this is because batteries and charging are almost always what breaks on computers these days, so I'd like to be able to get by entirely without batteries, just using solar panels, like a solar calculator. http://canonical.org/~kragen/sw/zorzpad.git/ http://canonical.org/~kragen/sw/zorzpad.git/ has some preliminary research into that.

MomsAVoxell 1y ago
Thanks for sharing your awesome notes.. I will devour these eagerly and learn from your journey so far. I don't mind lower power if it means I can get off the grid, and especially if I can have a small fleet of devices for the purpose of.. I'm already doing myself of my development work on the uConsole - it's not a fast PC, nor a beast in any sense, but it does function just fine for my use case. I could see an ARM64 cluster being solar powered with workable results. I agree .. the idea of a battery-less solar calculator-type computer would be grand. Lets see how long it takes for someone to design a viable product around this idea ..
- kragen 1y ago
  There are a lot of levels of "not a fast PC", though. My power budget for the Zorzpad is one milliwatt, at which I think the Ambiq Apollo3 (an ARM Cortex-M4F) can deliver 20 MIPS, roughly equivalent to a Pentium-100 or a SPARC 5. It has 384KiB of RAM. The uConsole (https://www.clockworkpi.com/uconsole https://www.clockworkpi.com/uconsole ?) has at a minimum a 64-bit 1GHz RISC-V processor, on the order of 800 MIPS, 40 times as fast. Ambiq doesn't make ARM64 hardware. My theory here (and maybe this is just the inflexibility of old age, treating my own experiences as gospel) is that there's a kind of phase transition in personal computers along the path between, say, a PDP-8 or an Altair, and a SPARC 1 or a 486: ‣ PDP-8 or Altair (≈0.01 MIPS, ≈0.01 MB RAM): self-hosted development is almost impossible; you need a big computer like a PDP-10 to compile the operating system, although the small computer is capable enough to run an assembler, a BASIC interpreter, and non-optimizing compilers for languages like Fortran. Applications like word processing and spreadsheets can be sort of approximated. ‣ IBM PC, Apple //GS, or PDP-11/70 (≈0.1 MIPS, ≈0.1 MB RAM): self-hosted development is comfortable and responsive in languages like C or Pascal. Viable applications include things like 2-D mechanical CAD, word processing, version control, and spreadsheets. GUIs are clunky because redrawing the entire low-resolution screen takes a second or so. ‣ Macintosh 512K, Sun 3/60, 80486 (≈1 MIPS, ≈1 MB RAM): mouse-driven GUIs have reached basically the same form we use them in today on the desktop. Self-hosted development is the only way to go, and higher-level languages like PostScript, Emacs Lisp, Tcl, HyperTalk, Visual Basic, and Perl are popular. Viable applications include things like VLSI simulation, 3-D modeling, and Web browsers. So somewhere in that range there's a phase transition between "basically a peripheral of a larger computer" and "GUI workstation". The Apollo3, being a microcontroller, is balanced like a microcontroller rather than a personal computer: 100 MIPS (with FPU), but only 0.4 MB RAM. So it has the RAM of an Amiga 500 or a Mac 512, but the CPU speed of a SPARC 5, a Pentium 60, or a PowerMac 8100. (See https://netlib.org/performance/html/dhrystone.data.col0.html https://netlib.org/performance/html/dhrystone.data.col0.html.) My speculation is that, coupled with the much faster mass storage speeds available with NAND Flash, this ought to be enough for a comfortable self-hosted development experience. I mean, I wrote GUI apps and browsed the Web on a SPARC 5 and a 5x86-133. I suspect that the structure of the system software will have to be significantly different. (See https://rossumblog.com/ https://rossumblog.com/ for some examples of what people have done with small microcontrollers that are capable of running on low power.) But the uConsole will still be on the order of 10 times faster, and consequently (if we hold the underlying implementation technology constant) dissipate on the order of 10 times as much energy. Considering that it's using conventional CMOS instead of Ambiq's subthreshold process, the ratio is probably closer to 50:1.