kens

8 ms·

1.
by kens 4d ago
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 claime
2.
by kens 4d ago
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.
3.
by kens 4d ago
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.
4.
by kens 4d ago
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, w
5.
by kens 4d ago
The Cray-1 (1976) was probably the first 64-bit CPU.
6.
by kens 4d ago
Author here for your 8087 questions...
7.
by kens 6d ago
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-
8.
by kens 11d ago
Curiously, Eswatini (formerly Swaziland) is capitalized eSwatini, as if it is an e-commerce site.
9.
by kens 11d ago
Curious fact: France's longest border is with Brazil.
10.
by kens 14d ago
Most horrifying is a 2014 Science paper on Ebola with 58 authors, 5 of whom died of Ebola before publication. https://www.science.org/content/article/ebolas-heavy-toll-st...
11.
by kens 16d ago
Yes, even Rojas says, "From a practical perspective, and in the way the Z3 was really programmed, it was not equivalent to modern computers." https://www.researchgate.net/publication/3330654_How_to_make...
12.
by kens 16d ago
The argument that the Z3 is universal "was an impressive party trick, but diverged entirely from the way the machine was designed, how it was actually used, or indeed from anything that would have made sense in the 1940s." Source:
13.
by kens 16d ago
There are different ways of implementing core memory. The "traditional" way uses the inhibit line. The module I examined uses a "2½D" approach, which is what you originally pictured: separate current drivers for each bit
14.
by kens 17d ago
The Polaris ballistic missile computer, developed at the MIT Instrumentation Laboratory, was the predecessor to the Apollo Guidance Computer. It used germanium transistors along with magnetic core shift registers for memory. The Polaris com
15.
by kens 17d ago
I assume you're interested in magnetic core logic computers in general, not specifically Parametrons. In the late 1950s, NASA considered core-transistor logic for a spacecraft navigation computer due to its lower power consumption. The
16.
by kens 17d ago
The main reason was the "inhibit recovery problem". The inhibit line required a large current that went through all the cores. This caused electrical noise, requiring a delay while the noise settled down. Doing away with the inhib
17.
by kens 17d ago
Core memory is very resistant to radiation. When the Shuttle computers were upgraded to semiconductor memory, radiation became an issue. The solution was to add six extra bits of storage to each word and use ECC. A background process scanne
18.
by kens 17d ago
I've already written articles about the French computer and FRAM; enjoy :-) https://www.righto.com/2026/05/reverse-engineering-spacelab-... https://www.righto.com/2024/09/ramtron-fer
19.
by kens 17d ago
Author here for all your core memory questions...
20.
by kens 28d ago
One weird unit for angles is the mil, defined as 6400 mils in a circle. This unit is very useful for artillery, since 1 meter displacement at a distance of 1 km is 1 mil [†]. Thus, you can see how much you missed by, divide by the distance,
21.
by kens 1mo ago
The history of computing is usually described as a nice progression from vacuum tubes to transistors and then ICs. But parametrons are only one of the many forgotten technologies that popped up along the way. Magnetic core logic such as tra
22.
by kens 1mo ago
I wrote an article on the history of magnetic amplifiers: https://spectrum.ieee.org/the-vacuum-tubes-forgotten-rival The quick summary is that magnetic amplifiers started in the US in 1901, but Germany came up with much bet
23.
by kens 1mo ago
I'm too busy trying to reverse-engineer the Intel 8087 floating-point chip, although it would be interesting to look at this puzzle chip.
24.
by kens 1mo ago
Thanks for filling in the details! I figured that I was already going into too much history in my article :-)
25.
by kens 1mo ago
Cute, but the steps don't make sense. E.g. each cycle shows both an ion gun and wire deposition. But only the first layer would use the ion gun, and only the following layers would have metal deposited. (Front End of Line vs Back End o
26.
by kens 2mo ago
Author here. I've powered up another tube module from the IBM 604, so let me know if you have questions...
27.
by kens 2mo ago
It's kind of hopeless to try to prove that a microprocessor works according to spec, since you're dealing with physical objects in the real world. For instance, early versions of Intel's 386 processor had a 32-bit multiply pr
28.
by kens 2mo ago
Serious question: does Figure 1 in the article make sense to anyone? If you understand the symbols, do you look at the diagram and it's clear how logistics works?
29.
by kens 2mo ago
The short answer is the "14-day" rule, which doesn't allow development of the embryo beyond 14 days. The article gives specifics under the heading "Ethical and legal compliance"
30.
by kens 3mo ago
Oops, I've fixed that now.

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