During the first week and change of our vast national COVID-19 induced remote teaching experiment I made some notes on practices and improvised some equipment that has proved useful, and seems worth sharing with others.
This two week period I’ve primarily been running lab sessions to help my herd of mostly-Sophomores do and get sign off for a digital design lab exercise using Verilog to implement state machines, adapted slightly from our usual lab at this time in the semester.
Even though I haven’t done any work in that area in years, I got pulled into the Supercomputing conference again this year. Can’t complain, it’s always fun. UK’s combined booth looked good this year
Far corner is a little updated TinyTitan style Raspberry Pi cluster with a interactive CFD demo running on it that the CCS folks have been playing with, that thing in the leading corner is a cute flip-dot “quantum computer” model we built as a front-end for a 16-bit instance of Hank’s parallel bit-pattern computing system that can do quantum algorithms efficiently on a conventional platform – set in the corner of the booth like
He did surprisingly well with this approach.
The exhibit floor was even more dominated by cooling tech this year. Exciting finds are the coming of very open (Open Compute Project, Coreboot + Open Network Linux) white-box 100GBE switches at reasonable prices, Fujitsu’s A64fx ARM with SVE and obscene memory bandwidth parts actually landing in systems, and (just because it tickled me) pre-wired fully populated Clos topology 100G cable harnesses. The other dominant species was AI woo; my body is ready for AI Winter 3.0.
Google photos album of my annotated show floor photos is here.
I’ve been working with a number of Anycubic Linear Kossel / Kossel Plus (whatever branding they’re using when you look) 3D printers for the last couple months, including one I bought personally. While I’m overall extremely pleased with them, there are a whole bunch of notes, fixes, and improvements I feel like should be collected somewhere.
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Some months ago I decided I wanted to play with an IBM Selectric typewriter, and after some fuckery, obtained and started working on an example of the dual-pitch, correcting Selectric II I find most appealing. At some point there will be an extended post about that, but 1. I’m not entirely sure I know what I’m talking about yet, and 2. Too much writing at the time I was working on it. This post is not about the machine, just the cover I made for it.
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Or, three hours enjoyably lost to a visit from the bad idea fairy.
My PhD advisor and I were chatting in the lab today and had an idea that it would be interesting to try to drip/jet a bit of water onto just-extruded filament, ideally in small enough quantity that it phase changed and flashed off with all the excess energy, in order to allow printing unreasonable unsupported structures.
It unfortunately doesn’t look like it will be practical, but we got a PoC-grade implementation in a few hours and it seemed worth a quick write-up to document our experiment for the interwebz.
Continue readingI’ve been carrying a series of slightly-customized 3D printed bolt-type bladekeys since 2014. Despite being printed PLA, I’ve only had to print a new one once every several years – I wasn’t keeping good records but I think this is my third plastic body, second #8-32 “Chicago Binding Post,” and I upgraded the type of pocket clip at some point. I’m yet to have a catastrophic failure. The setup essentially eliminates key jingle, poking, or wear on pocket facings, while still being easy to tap check and use. The only slight downside to this setup is that when I attach a car key and put it in the vehicle, the blade-key dangles at knee height and occasionally grabs a leg hair – if I drove more I’d probably tweak how I attach the car key to fix that.
Pictures from the first one I carried in 2014, and the most recent swap out, induced by it “getting loose” and letting the stack of keys flip forward in my pocket – which turned out to be the result of several cracks in the plastic body. Plus, flexing that the bitting and labels are both obscured when closed, which I suppose is a minor security feature, especially when posting pictures on the Internet.
At this point I’d buy one of the fancy ones just to support the designer, but my desired size falls in between the models they do commercially (I use 15mm W x 58 L, closest sizes are 12mm W and 19mm W). Maybe sometime I’ll get ambitious and cut one in a different material on the router.
I just picked up an Aneng AN8009 DMM as an upgrade to the cheap, cheap (but surprisingly OK) Circuit Specialists branded MY-68 I’ve had as my home on-desk approxometer for ages. It’s a nice meter for $30ish, and can be readily hacked to improve its performance. I tend to point people to mid-range Uni-T DMMs when they asked for decent hobby meters, but now I might switch to one of these plus one of those little $10 Atmega328 based component testers cloned everywhere for ~$10 as basic electronics lab instruments.
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We were doing a bit of beginning-of-summer lab maintenance and one of the projects was to figure out why the MakerGear M2 (Which has been heavily modified over the years, Azteeg x5 mini motherboard, E3D hotend, etc.) was behaving so strangely.
Well… there’s your problem.
Fresh 0.35mm nozzle next to the bored out, abraded down corpse of a nozzle that we’ve, in retrospect, been running for something like 3 years. Turns out printers work much better when the nozzle aperture is roughly the size it’s supposed to be.
Still seeing some odd temperature fluctuation, but … look at that thing.
That MSEE that I was going to finish in 2011, 2013, and 2015? I blew a couple months in the last year to get all the ducks in a row and actually collected it before the credits expired. Huge thanks to Dr. Aaron Cramer, the current DGS for UK’s ECE department who went to great lengths to deal with the bureaucratic issues my lackadaisical attitude about credentials created.
Thesis is “A Compiler Target Model for Line Associative Registers” document and defense slides with notes linked.
The LARs design is fundamentally interesting, but the compilation work the MS is based on is not my favorite work I’ve done. The core initial assumption (that LAR allocation and register allocation were more-or-less the same problem) turned out to be very, very wrong, and the implications of that wrong assumption turned out to be far reaching, turning a 2-year MS into a decade-long ramble. It’s not as depressing as I thought it would be when I tried to finish in 2015 (and was blocked by bureaucratic fuckery) because I did eventually determine that LARs aren’t subject to the “you can’t statically schedule around dynamic memory behavior” thing that doomed VLIWs, and in fact LAR allocation can be done greedily in ways that register allocation cannot.
The thesis is more or less assembled from three false starts plus the final effort; my initial research start with the wrong assumptions, my “oh, we’re wrong, but it’s OK” pass, and my “oh shit, we’re screwed, this won’t work and there his historical evidence to show it” pass, plus the final “I’ve figured out how this is tractable and possibly even desirable, but I’m out of time and fucks, so here’s the rough solution” pass.
I formatted the thesis in LaTeX (of course), using the ukthesis.cls class I found on the UK Math site that Eric Stokes, a former student, made a decade and change ago since UK is too chickenshit to provide a valid one of their own. I did have to hack it a little bit, turn off some features, tweak the front matter, etc. to make it acceptable to the graduate school, and update a few things (eg. adjusted to use biber for references). There are a few things in the document that should be in the class, and things in the class that should be in the document, but the easy-to-fix stuff is fixed. Minimal example pulled from the accepted version with makefile and such here to save future students the extra annoyance.
The presentation is in beamer using the Owl theme, which was a delightful recent discovery – someone has made a beamer color scheme with a dark background and colors that actually look good on a projector. I (much to one of my committee member’s disappointment) went with the bullets-to-keep-me-on-track-while-I-talk style slides instead of my usual “amusing semi-relevant pictures to key off of” scheme.
It’s nice to be done and only have one, significantly less depressing, long-term academic project people are grumpy about my progress on.
