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kens

23,458 karma · joined October 11, 2010

Ken Shirriff ken.shirriff@gmail.com https://righto.com @righto.com on Bluesky @oldbytes.space/@kenshirriff on Mastodon
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kens··on Every AI model has the same "controversial" take on humans
I took a quick look at the data, and it doesn't support the conclusions. The thesis is that AI models have the take: "We pick what our group believes, then invent the reasons." However, GPT-6 Astra said, "Humanity’s biggest moral failure is the talent for making convenience look like principle." That statement has nothing to do with group beliefs or conformity. At best, you could count it as a half-match, since it deals with invented reasons.
kens··on Where Wealth Is Moving in America (2023)
That chart is extremely confusing because it mixes up income and wealth, which are two different things.
kens··on The Intel 8087 chip: floating-point addition and subtraction
I describe the 8087 instruction decoding here: https://www.righto.com/2026/02/8087-instruction-decoding.htm...
kens··on The Intel 8087 chip: floating-point addition and subtraction
Thanks! I guess I didn't have my glasses on when I read that number :-)
kens··on The Intel 8087 chip: floating-point addition and subtraction
Author here with another 8087 article. What part of the 8087 should I look at next?
kens··on What was a Token Ring network?
> Datapoint, a pioneer in office automation using small computers

In 1970, Datapoint created a desktop computer, the Datapoint 2200, with an 8-bit TTL processor. Intel created a microprocessor version of this processor for Datapoint, called the Intel 8008. Datapoint decided to stick with TTL, so Intel ended up selling the 8008 as a general-purpose microprocessor. Intel improved it to make the 8080, then made a 16-bit version, the 8086, as a stopgap product until the iAPX 432 micro-mainframe was ready. The iAPX 432 was a disaster and that's how you ended up with x86.

kens··on Secret of Orange Cats Revealed After 60-Year Search
I thought this seemed familiar; it's a rehash of a 2024 discovery: https://www.science.org/content/article/gene-behind-orange-f...
kens··on I paid people to try and follow my README
> "They were the ones who caught the mistakes that no spell chequer could."

I thought that maybe "spell chequer" was the valid British term, which would be interesting, so I searched but it isn't. It turns out that the joke here is that "chequer" is a valid British word, so a word-based spell checker won't flag "spell chequer", so it's self-referential. I see why people found his jokes actively confusing.

kens··on A 1980s filter chip that uses switched capacitors
Thanks, that explains the part number. I never would have guessed that the logo was included.
kens··on A 1980s filter chip that uses switched capacitors
On-chip decoupling capacitors do get used [1]. The main problem is that they take up a lot of valuable die space for not much capacitance.

[1] https://doi.org/10.1109/SBCCI.2003.1232837

kens··on Knuth reward check
I lost one of mine but Knuth kindly sent me a replacement.
kens··on OpenSCAD the Programmers Solid 3D CAD Modeller
As a programmer, I second this. Systems like Blender are inscrutable to me, but in OpenSCAD I just write some loops. I get what I want and it's easy to tweak.
kens··on A 1980s filter chip that uses switched capacitors
Author here for your filter questions...
kens··on The Mathocalypse
> I think the next step is to demand that proofs either be human-scale or they prove that a human-scale proof is impossible and the machine proof is as good as it gets.

In 1976, the proof of the Four Color Theorem was controversial because it was done with a computer examining over 1000 cases by brute force and was essentially not comprehensible by humans. But mathematicians ended up accepting it. So mathematics has a 50-year precedent of not requiring human-scale proofs. How is the current situation different?

(Disclaimer: Apologies if this sounds dismissive or argumentative. I genuinely think that the Four Color Theorem should play a role in these discussions and suspect that many people are unaware of the controversy over it.)

kens··on Former SR-71 engineer talks NASA's Blackbird revival program
Ha ha, that would be a fun project. We might need a bigger basement, though :-)
kens··on Reverse-engineering the Intel 8087's tangent algorithm: more than CORDIC
The 8087 is probably enough floating point for a while :-)
kens··on Reverse-engineering the Intel 8087's tangent algorithm: more than CORDIC
Author here for your 8087 questions...
kens··on We're gonna need a lot more mathematicians
5000 engineers for the Pentium Pro?? Bob Colwell, chief architect of the Pentium Pro, says 450+ people with over 400 design and validation engineers. Source: "The Pentium Chronicles", pages xvi and 2.
kens··on The UV index is not the warm sensation of sunlight on bare skin
The details of UV damage are interesting. You can think of DNA as a sequence of four letters: C, G, A, and T. If there are two neighboring T's, UV can move a bond, linking the two T's together (i.e. thymine dimerization). If you're in the sun, each skin cell gets 50-100 of these pairs created per second (which is much higher than I expected). Enzymes fix most of these errors, but sometimes the errors will cause problems during DNA replication and you can end up with mutations.

Details: https://pdb101.rcsb.org/motm/91

kens··on What Sun got wrong
I worked at Sun from 1995 to 2004. My take is that Sun had major structural problems all along, but as long as money streamed in from the tech bubble, these issues could be ignored. When the tech bubble ended, it was too late to fix the problems.

One big problem was that there was no cooperation inside Sun. Groups in Sun kind of viewed HP as a competitor, kind of viewed SGI as a competitor, but the real competitor to be destroyed was that other group in Sun. The leaders of the project I worked on spent most of their time in political battles, trying to acquire or outmaneuver the other teams working on similar projects.

Another problem was that the main parts of Sun had conflicting strategies. The Solaris/SunSoft division wanted to run on SPARC, x86, and Power PC for the largest market. The SPARC division, of course, wanted none of that. The hardware division wanted to make expensive servers, but the other teams saw cheaper hardware as the right direction. The market ended up moving to cheap rack-mounted Linux x86 servers, so nobody at Sun won in the end.

kens··on How Hacker News ranking works: scoring, controversy, and penalties (2013)
Author here. I don't know why this popped up 13 years later, but hi :-)
kens··on Microcode in Intel's 8087 floating-point chip: the scale instruction
I think the emulation code was a rewrite in 8086 assembly language. An 8087 microcode emulator would be slow and difficult. One of the Opcode Collective people is looking at the emulator now, so there may be more details later. Intel claimed that the emulator completely and exactly duplicated the 8087 functionality, so it would be interesting to see if it is 100% accurate or if they missed any corner cases.
kens··on Microcode in Intel's 8087 floating-point chip: the scale instruction
Yes, it's one microinstruction per cycle, except there is a 1-cycle delay for branches, adds, and shifts. And some micro-instructions loop, so they can take a bunch of cycles.
kens··on Microcode in Intel's 8087 floating-point chip: the scale instruction
I forgot about the IBM 7030 Stretch (1961), which was also 64 bits. The NORC (Naval Ordnance Research Calculator) (1954) had 16 decimal digits, which is sort of 64 bits.
kens··on Microcode in Intel's 8087 floating-point chip: the scale instruction
I've looked at some early calculators and they are a whole different world of weirdness. They used decimal arithmetic (BCD) because it's a lot easier than converting between binary and decimal. The first calculators were serial, with a 1-bit adder and shift registers and bits constantly in motion. The Sinclair Scientific calculator used TI's strange 4-bit architecture along with terrible algorithms.
kens··on Microcode in Intel's 8087 floating-point chip: the scale instruction
The Cray-1 (1976) was probably the first 64-bit CPU.
kens··on Microcode in Intel's 8087 floating-point chip: the scale instruction
Author here for your 8087 questions...
kens··on OpenAI’s Navier-Stokes release included a Lean 4 formal proof
It would be nice if someone used AI and/or Lean to sort out the abc conjecture, an important unsolved problem in Diophantine analysis. A mathematician (Mochizuki) claimed to have proven it in 2012 using a new theory called "Inter-universal Teichmüller theory" that almost nobody understands. Some mathematicians think the proof is correct while the majority don't. So the conjecture is in this annoying limbo where its status is a social construct rather than a decided fact.

https://en.wikipedia.org/wiki/Abc_conjecture

kens··on Topologist's Map of the World
Curiously, Eswatini (formerly Swaziland) is capitalized eSwatini, as if it is an e-commerce site.
kens··on Private German rocket makes history, reaches orbit from European soil
Curious fact: France's longest border is with Brazil.
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