--- Log opened Sat Dec 25 00:00:11 2021
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04:13 < maaku> lsneff: have you seen the j1 cpu? https://www.excamera.com/sphinx/fpga-j1.html
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07:53 < L29Ah> -j1
09:17 < lsneff> That’s neat
09:18 < lsneff> Been interested in cpu design recently, I think better hardware description languages could make it orders of magnitude easier
09:18 < lsneff> Just like how rust made it possible to write a parallel css engine
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13:38 < docl> .t https://www.sciencedirect.com/science/article/pii/S2542435117301782
13:38 < saxo> Photoelectric Solar Power Revisited - ScienceDirect
13:39 < docl> "In a photoelectric solar power device, instead of this barrier being a semiconductor band gap, it is the work function φ."
13:43 < docl> so those are two different things, which is what makes PV work at lower frequencies vs photoemissive
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14:08 < docl> "It is essentially a planar transparent anode and photocathode separated by a gap d. Sunlight passes through the transparent anode and a fraction of these incident photons causes photoemission from the photocathode."
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15:07 < maaku> lsneff: https://clash-lang.org
15:07 < maaku> .title
15:07 < saxo> Clash: Home
15:07 < maaku> "Clash is a functional hardware description language that borrows both its syntax and semantics from the functional programming language Haskell. It provides a familiar structural design approach to both combinational and synchronous sequential circuits. The Clash compiler transforms these high-level descriptions to low-level synthesizable VHDL, Verilog, or SystemVerilog."
15:08 < lsneff> Yep, I’m aware of clash
15:08 < lsneff> I don’t think it’s enough
15:08 < lsneff> Bluespec is closer, but it needs an overhaul
15:08 < maaku> lsneff: but the J1 cpu is more than just random cpu design. it's really compact and yet blurs the edge between hardware and firmware
15:08 < maaku> one of my favorite bits of hardware engineering
15:10 < maaku> that's usually the case for stuff like this which emerged out of practical necessity rather than realizing some deep theoretical foundation
15:26 < lsneff> It is really impressive how small it is
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16:08 < kanzure> https://github.com/lowrisc/opentitan
16:19 < lsneff> I think a rework of bluespec with some changes and modern syntax along with a package manager for it could be widely used.
16:19 < lsneff> It’s about the right level of abstraction
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18:09 < docl> muurkha: regarding keeping the anode cool, looks like realistic temps are only a small fraction of 1 eV. the rule of thumb seems to be temperature in kelvin divided by 11500 gives you eV. high vs low wf materials are multiple eVs apart
18:09 < docl> .t https://www.researchgate.net/post/How-to-measure-temperature-in-eV
18:09 < saxo> How to measure temperature in eV ?
18:09 < docl> "Just divide the temperature in kelvin by 11500 to get the approximate temperature in eV."
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18:42 < nsh> (if temperature were expressible in terms of pure numbers and electron volts [mass] then there would only be three natural units)
18:42 < nsh> which is, you know, substantial if substantive :)
20:14 < lsneff> I’m not sure if this is relevant, but you cannot generally extract power from a hot object, there’s gotta be a gradient
20:44 < docl> .wik Thermionic_emission
20:44 < saxo> "Thermionic emission is the liberation of electrons from an electrode by virtue of its temperature (releasing of energy supplied by heat)." - https://en.wikipedia.org/wiki/Thermionic_emission
20:50 < docl> looks like they have to use a field effect to make this work. neutral metals would need unrealistic temperatures to trigger emission (even cesium, which has a work function of 1.9)
20:52 < docl> "In electron emission devices, especially electron guns, the thermionic electron emitter will be biased negative relative to its surroundings. This creates an electric field of magnitude F at the emitter surface. Without the field, the surface barrier seen by an escaping Fermi-level electron has height W equal to the local work-function. The electric field lowers the surface barrier by an amount ΔW, 
20:52 < docl> and increases the emission current. This is known as the Schottky effect (named for Walter H. Schottky) or field enhanced thermionic emission."
20:52 < docl> man, my knowledge on this is patchy... at least I'm learning
20:53 < nsh> for flow you need a gradient. for efficient flow you need an impedance matched network making a circuit about the gradient
20:53 < nsh> and to match impedances you tune 
20:54 < nsh> when the impedance of the load is the complex conjugate of the impedance of the source then all power is transmitted and no power is reflected
20:55 < nsh> in the limit this depends on all the characteristics of the system. for practicality we discretise and use lumped parameters 
21:07 < docl> what I'm thinking is that hot objects can emit electrons when hit by light at relatively lower frequencies, i.e. the energy needed to eject the electron includes the photon as well as any thermal energy in the object. so a block of carbon with work function of ~5eV would need 248 nm or shorter (UVC) unless a) it is very hot or b) the object has a bias voltage wrt its surroundings
21:20 < docl> 58000K would be emitting vast amounts of high energy photons so I'm pretty sure just heating up a block of carbon until it emits electrons in the neutral state doesn't work. but putting it at -5V relative to a nearby grate is doable
--- Log closed Sun Dec 26 00:00:12 2021