Hacker News: dbcurtis

New comment by dbcurtis in "Come for ENIAC, Stay for UNIVAC and Skeduflo"

dbcurtis — Thu, 13 Aug 2026 20:11:56 +0000

I worked at the Roseville, MN, plant in the early 80's as a CPU designer. 100K ECL. The machine was the Integrated Scientific Processor, an attached processor that could be added to an 1100/80 system. Max configuration was 4 CPU's (model 1100/84) plus 2 ISPs. The ISP was a vector processor that had approximately the same peak performance of a CRAY-1, and higher average performance. (In part because we handled the "short vector problem" more elegantly, so the last few elements of every long vector didn't pay a time penalty for dealing with the tail end of a long vector. There were a few other architectural tweaks that contributed.)

The program was not a success. Reason 1: Oil prices came way down, so seismic data reduction and reservoir simulation markets dried up, Reason 2: Univac management was timid and slow at decision-making and starved the project. Had we been properly resourced and delivered a couple years earlier, things could have been different.

Anyway, it was a hugely fun CPU to work on.

New comment by dbcurtis in "Elevators"

dbcurtis — Fri, 31 Jul 2026 17:07:49 +0000

Most systems to that. Empty-cab strategy is a programming option in the controller. If all cabs are idle (very rare) they are typically spread out.

New comment by dbcurtis in "Elevators"

dbcurtis — Fri, 31 Jul 2026 17:06:22 +0000

This does happen. I also once worked on a destination-dispatch elevator system installed in a high-end condo building (high-end, as in concierge and parking valet for residents). Anyway... the resident's key card would of course automatically call a cab to take them to their unit's floor, but also the security system had entries for things like "dog owner" and "allergic to dogs" so that the DD system would never schedule them together for the same cab.

New comment by dbcurtis in "Elevators"

dbcurtis — Fri, 31 Jul 2026 17:01:22 +0000

It's pretty much throughput. The cap-ex of a single cab swamps any other cost, so the only way to reduce total number of cabs is optimizing for throughput.

New comment by dbcurtis in "Elevators"

dbcurtis — Fri, 31 Jul 2026 16:59:37 +0000

One other thing to add: It isn't the elevator scheduling software being obtuse, that software gets a huge amount of thought. But elevators are expensive, and building owners do not over-spend on a whim. Typically, they have just enough cabs (if that) to handle the expected load.

New comment by dbcurtis in "Elevators"

dbcurtis — Fri, 31 Jul 2026 16:55:06 +0000

I have done several third-party elevator integrations (software that talks to the elevator controller) for coordinating other equipment with the elevator. One thing that always struck me once I had full visibility into the location and motion of all the elevator cabs is how busily they are scheduled. Waiting in the elevator lobby for a cab seems to take forever, but viewed from the dispatch side, it is a flurry of activity and cabs are rarely idle during any hours the building is normally occupied. It is easy to nerd out just watching the status panel.

Another thing I learned: If an elevator mechanic says: "I'll meet you first thing in the morning." He means something like 4:00AM. They want to get in and out before people start arriving to start their day.

New comment by dbcurtis in "Forth"

dbcurtis — Mon, 27 Jul 2026 23:28:28 +0000

even more pedantically, would remove 3 and 4 from the stack before pushing 7

New comment by dbcurtis in "Shay Locomotives"

dbcurtis — Mon, 27 Jul 2026 17:07:06 +0000

If you are in Sili Valley and want to see a Shay, cross the hill to Felton to Roaring Camp for one of their excursion trains.

New comment by dbcurtis in "Farmer, marketer at odds over sales of white nectarines"

dbcurtis — Fri, 03 Jul 2026 20:32:28 +0000

Almost true. For many plants, a hybrid is naturally unstable, and can often be stabilized with one extra cross. (But isn't, as it serves as intellectual property protection for the seed company.) But some plants, soy beans being a biggest cash-crop example, can not be bred to be unstable. (See my comment above about Monsanto Roundup-Ready beans.)

New comment by dbcurtis in "Farmer, marketer at odds over sales of white nectarines"

dbcurtis — Fri, 03 Jul 2026 20:29:11 +0000

Well, as an Iowa farm boy (and farm land owner) I have a more nuanced view. There have been hybrid maizes for many decades. It is possible to create unstable hybrids of normal field corns, which serves as a form of intellectual property protection for seed companies. As a farmer, you certainly can go out and plant heirloom varieties that can self-reproduce if you so choose. At which point, the choice of buying hybrid seed versus planting an heirloom variety is a simple business decision. Now with soy beans, on the other hand, it is not possible to create an unstable hybrid. Even hybrid soy beans can be saved and planted. Which is the direct root of the insanity around Monsanto's Roundup-Ready hybrid seed licensing scheme, and all the notorious law suits around that. We would be better off if Monsanto could sell an unstable soy hybrid. That would eliminate all the craziness that the licensing system creates.

New comment by dbcurtis in "Show HN: Teach your kids perfect pitch"

dbcurtis — Mon, 22 Jun 2026 01:02:28 +0000

My kiddo has perfect pitch, and for them listening to a baroque period organ is kind of trippy because back in those days A was more like 436 Hz than 440. OTOH, absolute pitch means that learning a fiddle tune by ear takes only a couple of choruses. These days, they are grooving on Angine de Poitrine, so somehow they are OK with microtonal scales. It probably varies from person to person, but I can see where perfect pitch could give you another way to be annoyed by the world.

New comment by dbcurtis in "Copper transport drug restores memory and clears toxic Alzheimer's proteins"

dbcurtis — Mon, 15 Jun 2026 16:17:36 +0000

> Alzheimer’s is driven by the buildup of toxic proteins called amyloid-beta.

Isn't the current thinking that amyloid-beta buildup is a marker, not a cause? The therapy may be working here, but it isn't clear whether clearing amyloid-beta proteins is the mechanism or an outcome.

New comment by dbcurtis in "Hindenburg’s Smoking Room"

dbcurtis — Mon, 18 May 2026 05:58:25 +0000

It was part of the culture in the 1960's, and only started to change somewhat during the 1970's. Everybody had ash trays, even in non-smoking households, so that you could bring them out for guests. Nobody gave it a second thought. Clay ash trays were common elementary school arts & crafts projects.

One of the things that reminded me of how much a part of the culture it was, is when we visited the Computer History Museum. The SAGE system display had several operator consoles -- each with an ash tray and an automotive-type cigarette lighter in the panel.

New comment by dbcurtis in "Two EA-18 fighter jets collide at Mountain Home airshow, pilots ejected safely"

dbcurtis — Mon, 18 May 2026 00:10:01 +0000

Do we know if the pilots are OK? Yes, ejection can save your life, but even in a best-case scenario the forces on the human body are incredibly ugly. I know a former combat-rated RAF pilot that had to eject from a Harrier because of a low-altitude bird strike. After 6 months in the infirmary, he emerged 2cm shorter, combat rating gone forever.

New comment by dbcurtis in "GenCAD"

dbcurtis — Mon, 18 May 2026 00:04:00 +0000

> Which CAD program? I'm confused

Clue here: > Our proposed GenCAD architecture...

So, at this point, it seems like this will work with all CAD programs, since they have yet to encounter any systems that they can't work with. More seriously, my guess would be whatever one is available for free in their lab. Kind of standard operating procedure for academic projects -- do a proof of concept, make a video that avoids known bugs, get a grade, push source to git, graduate. Good ideas come out of that... production code... eh... maybe.

More likely someone ends up in the situation that my kid did, previous graduate student's git repo is stale by 2 versions of C++, and 4 versions of ROS, and neither of the two unit tests still work after porting.

New comment by dbcurtis in "Is my blue your blue? (2024)"

dbcurtis — Mon, 27 Apr 2026 21:43:52 +0000

No. I got it set for distance vision. There are modern implants that are "multi-focal". But they work by spreading out the light, so everything is less bright at any distance. My two pieces of anecdata are: 1. A friend with multi-focal implants says that he needs a very bright light for reading now. Which is one of the reasons I avoided multi-focal. 2. My optometrist got multi-focal, and he noted that it required retraining his brain somewhat, because now instead of accommodation providing focus, focus requires mental attention to the subject of interest.

Cataract implant technology is moving very fast, and my data is about 5 years old, so YMMV.

New comment by dbcurtis in "Is my blue your blue?"

dbcurtis — Mon, 27 Apr 2026 21:37:50 +0000

It seems to me there is a broad range of "normal", as in well within the standard spec sheet tolerances for humans. It is more about what is average or median.

New comment by dbcurtis in "Is my blue your blue?"

dbcurtis — Mon, 27 Apr 2026 21:33:16 +0000

Who else tried with both eyes? A few years ago I had an implant to treat cataracts. It was notable at the time that the "new" eye was less yellow-tinted than the aged-in-place eye. I was told that the lens does yellow with age. Over time, my brain mostly adjusted, but on this test I did notice a subtle hue difference between eyes. Did anyone else try that experiment?

New comment by dbcurtis in "YouTube now world's largest media company, topping Disney"

dbcurtis — Tue, 14 Apr 2026 23:33:37 +0000

> Rarely(never?) have I found new knowledge on youtube, however its a great source of joy/emotions/slop.

I suspect you are not looking very hard. I have learned a tremendous amount about everything from stone cutting to metalworking to welding to Kalman filters to linear algebra. There is a lot out there. The main annoyance I have is keeping AI slop out of my feed so that I can instead learn from genuine experts. There is a huge amount out there.

New comment by dbcurtis in "Uncharted island soon to appear on nautical charts"

dbcurtis — Mon, 13 Apr 2026 04:23:46 +0000

The burning question is whether or not it qualifies as a new DXCC entity.