Since finally being rid of my PhD work, I’ve been hitting a bunch of projects that have been on my TODO list for ages.
The oldest so far is this PSU which has been sitting for …decades… in my parts pile with some compatible machines, and I’ve always intended to try rebuilding it. It died with a “ticking” symptom some time in the mid-00s.
I finally got around to it this week, and it wasn’t a bad job. About $10 of parts, a few hours of work, and it’s back in action. Rebuild details below.
If you have an OG Xbox sitting on a shelf somewhere, this is your reminder to pull the clock capacitor and clean up whatever corrosive goo it has already vomited out.
I was talking old video games with a student in one of my labs this week and it reminded me that this is one of the many projects I’ve been meaning to get to but haven’t had time for for the last several years.
Microsoft used some cheap 2.5V 1F early super caps which will inevitably fail and spray electrolyte on your motherboard, because they made some cost-cutting choices about the RTC, so now everyone with an old Xbox has to fix it.
iFixit has their usual helpful guide for pulling it apart, and the ConsoleMods wiki has the details on the clock cap situation. I didn’t even bother replacing the one in mine, I don’t pull my old Xbox out enough for it to matter.
Remove dead cap, clean residue thoroughly, move on. It’s a quick job.
Having now collected two graduate degrees myself, and been related many stories by friends and acquaintances doing grad school at UK, some advice for those behind me.
UK’s graduate school is the absolute archetype of the rule of thumb that, at UK, every individual you deal with will be nice and helpful, but as an organization they’re the most useless, obstructive motherfuckers you’ll ever have the displeasure of dealing with. You will never find an individual to punch in the face when something deserving happens, because responsibility has been diluted sufficiently that there isn’t usually an individual bad actor responsible for whatever bullshit is going on; the problem is that there are half a dozen overpaid people with inflated titles not dealing with the thing, and an assortment of folks in lower-titled, public-facing positions having to scramble to make things work around the administrative dysfunction.
The fact that UK just went into administrative bloat overdrive by dissolving the faculty senate with no concrete plans to replace their functions, then started hiring random assholes who don’t even have the context to know how things have to work to take over matters the senate used to handle has made it even worse this year than usual.
Detailed Notes Below
It took another round of “longer than expected” because, while I passed my defense at the end of July, I had some requests to make significant changes to the dissertation before submitting my final copy, and that didn’t get wrapped up until early September with my advisor paying meaningful attention to what I was doing for the first time in years.
I ended up having to include a lot of the modern academic hype-spewing, stake-claiming bullshit I’ve developed a deep distaste for, but even with that I’ll admit it’s a much better document overall after the rewrite. It looks less negative than the earlier drafts, because they were largely written before my last “I give up, I’ll try one more stupid thing” experiment finally turned up something reasonably compelling.
The copy of record of the dissertation is published, here are local PDF copies of the deck from my defense and my dissertation. More information below.
Then I had several weeks of catch-up for all the many things in my life I’ve been shorting time to get done, while I was having the apparently requisite back-and-forth with the graduate school about petty formatting matters, but it is done.
Continue readingThe largest reason I’ve been starving every one of my other interests, like posting here, for the last several years is finally wrapping up, and looks like it will get me a PhD in Computer Science.
Wednesday July 24, 2024. 1:00PM. 101 Davis Marksbury Building.
Title: Post-Capture Synthesis of Images Using Manipulable Integration Functions
Abstract:
Traditional photographic practice, as dictated by the properties of photochemical emulsion film, mechanical apparatus, and human operators, largely treats the sensitivity (gain) and integration interval as coarsely parameterized constants for the entire scene, set no later than the time of exposure. This frame-at-a-time capture and processing model permeates digital cameras and computer image processing.
Emerging imaging technologies, such as time domain continuous imaging (TDCI), quanta image sensors (QIS), event cameras, and conventional sensors augmented with computational processing and control, provide opportunities to break out of the frame-oriented paradigm and capture a stream of data describing changes to scene appearance over the capture interval with high temporal precision. Captured scene data can then be computationally post-processed to render images with user control over the time interval being sampled and the gain of integration, not just for each image rendered but for every site in each rendered image, allowing the user to ideally expose each portion of the scene. For example, in a scene that contains a mixture of moving elements some of which are more brightly lit, it becomes possible to render dark and light portions with different gains and potentially overlapping intervals, such that both have good contrast, neither one suffers motion blur, and little to no artifacting occurs at the interfaces.
This thesis represents a preliminary exploration of the properties, application, and tooling required to capture TDCI streams and render images from them in a paradigm that supports functional post-capture manipulation of time and gain.
So excited to be rid of this thing. It’s a genuinely nifty idea, and sort-of the idea I started out with, but I’m very tired of looking at it.
If any internet friends want to come watch me talk shit about it for ~1 hour, you’re welcome.
I’ll post my thesis and slides after it’s done.
A buddy of mine dropped me a link to TI’s new brushed DC motor driver with sensorless speed control, the DRV8214. I spent a few minutes trying to hunt down the mechanism they use to derive speed from back EMF because it’s such an intriguing idea, and the datasheet proper is slightly cagey abut it… but it looks like they’ve fundamentally figured out how to build in the sensing and control loop from the filtered ripple counter mechanism (PDF) they previously published a guide for doing with discrete H-bridge/current sense/op amp/comparitor ICs and an MSP430 microcontroller directly into a $3-in-single-quantity I2C addressable chip.
It even has stall detection that looks good enough to potentially use for sensor-less homing.
Interfacing to a host micro is fairly pin-and-peripheral intensive, but this seems like good magic.
Firefox has a facility to use native file pickers via xdg-portals, which most of the internet will tell you is set in a key in about:config called widget.use-xdg-desktop-portal. Quite some time ago, that was split into more granular keys so those instructions aren’t useful anymore.
I finally got irritated enough to look into it this morning, turns out now switching your file picker is now via the key widget.use-xdg-desktop-portal.file-picker with values “0” (never), “1” (always), “2” (auto, apparently meaning “when run from a Flatpack”). There are similar keys for open-uri, mime-handler, etc. Most of the documentation on the internet is still the old version, though (of course) the Arch Wiki page on the topic is correct and up to date, and I should have looked there instead of googling.
You have to have a suitable xdg-desktop-portal package installed to plumb the picker, which varies a bit from distribution-to-distribution and environment-to-environment, on Arch+KDE it’s xdg-desktop-portal-kde.
I find the whole portals arrangement architecturally ugly, but important thing is that I can get rid of that obnoxious buttons-on-the-top GTK filepicker dialog, which is both ugly and upside down from the rest of the universe.
There have been some intermittent issues with this site for the last few days because some shitheel has been hammering the server that hosts web-facing things for me with automated script-kiddy bullshit that my existing hardening didn’t automatically catch.
Roughly 10GB of it in the last week.
With user agents set to around 500,000 different Chrome versions.
I noticed because the (small) box has been OOM killing processes any time the stats tools look at the logs of this behavior.
Most of it came from one address (in the AliCloud IP allocation, as always. I’ll continue to half-pretend it’s just a compromised VM) so I cleaned up the worst of it by adding an nftables rule to drop anything from that saddr, and did a little filtering to the logs to fix the OOM situation.
I’ve also turned on some rate-limiting features in nginx, and rigged fail2ban to block repeated violators of the rate limit, so hopefully things are more permanently taken care of.
I was having Vulkan/Wine interaction issues when I had a minute to play a game the other night and flipped my big laptop (which has Intel/AMD Polaris12 dual graphics, both running the Mesa stack since AMD dropped Polaris support in amdvlk in the 2023.Q4 release) into a Plasma Wayland session (v5.27) to see if it helped. It did – making it the very first thing I’ve encountered that worked in Wayland and not X – so I’m rolling with the Plasma Wayland session for a couple days to see how things are. I have a little machine I’ve been playing with Hyprland on to check out the Wayland situation, and it’s been closing from “Linux 20 years ago” to “Linux 5 years ago” in terms of brokenness, so it seems plausible that one of the big two would be tolerable now.
I’m totally onboard that xf86->xorg is an unmaintainable mess for both legacy-codebase and design from a different era reasons, and it would be nice to start with something built on assumptions that match modern reality, but uh… over a decade in, Wayland is just getting to be less of a “almost a tech demo” and more of an “almost there.” If the devs can shut up about some bikeshedding that obstructs common use cases now over concerns about theoretical security issues or compatibility with yet-unimagined future interface models and implement widely-accepted solutions to the last few basic-fucking-features, it might actually matter before it too starts to exhibit wrong ancient assumptions and gets replaced, but it looks like they’ve missed the bus on a couple of those necessary standardizations.
Things I use regularly that are currently broken in KDE’s Plasma Wayland session in Nov. 2023:
The whole situation is silly. It’s a gigantic shell-game of trying to outsource the solutions to problems everyone already knew needed to be solved consistently because the ICCM and EWMH stuff for X represented decades of effort to do so, by the people best situated to actually solve the problems at the time when they could be solved in a general way.
I sometimes get the feeling reading the bug trackers that many of the Wayland people are building a display layer suitable for infotainment systems, kiosks, signage, and that sort of thing, and desktop functionality is an unfortunate extra thing some people are trying to force on them – which, financially, may be the case.
Look at this time crystal on shopgoodwill. A pristine Antec SX1030 case (or chieftech dragon or one of the other clones), painted metallic green with a window installed. Every commercial or DIY gaming PC in the first few years of the 2000s was in one of these. It even has a case badge from an unreliable (but I repeat myself) Chaintech nforce2 motherboard installed, and a visible QC stamp from 2000.
It’s probably pristine because it exists permanently in 2001 and we’re just perceiving it in the present. If you built a sleeper in it, when you were done installing the OS there would be a cracked copy of Halo already installed. Wherever the buyer puts it, a half empty bottle of Bawls will phase into existence somewhere in a 6ft radius.
