tingilinde

constants in a pentium

More reverse-engineering fun from Ken Shirriff.

snip

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Intel released the powerful Pentium processor in 1993, establishing a long-running brand of high-performance processors.1 The Pentium includes a floating-point unit that can rapidly compute functions such as sines, cosines, logarithms, and exponentials. But how does the Pentium compute these functions? Earlier Intel chips used binary algorithms called CORDIC, but the Pentium switched to polynomials to approximate these transcendental functions much faster. The polynomials have carefully-optimized coefficients that are stored in a special ROM inside the chip's floating-point unit. Even though the Pentium is a complex chip with 3.1 million transistors, it is possible to see these transistors under a microscope and read out these constants. The first part of this post discusses how the floating point constant ROM is implemented in hardware. The second part explains how the Pentium uses these constants to evaluate sin, log, and other functions.

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seamless rails

ah, thermite!

an expensive bug

Ken Shirriff on the silicon behind the infamous Pentium division bug

Great stuff if this sounds remotely interesting.

 

 

wartime production

A fascinating piece on WWII aircraft production.

snip

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Creating an aircraft industry capable of producing planes by the hundreds of thousands didn’t happen overnight, and on the eve of the war the industry was a tiny fraction of what it would grow into. In 1937 the U.S. produced around 3,100 aircraft, most of which were small private planes. Prior to the war the value of aircraft made in the U.S. was about one-fourth the value of cans produced, and just 3.5% of the value of cars produced. Despite the continuing escalation of the war in Europe, the U.S. was reluctant to prepare for large-scale mobilization. Existing mobilization plans assumed that any future war would be smaller in scale than World War I had been, and that only half of the already-small existing aircraft manufacturing capacity would be devoted to war production. As late as 1940 the U.S. military had just 2,665 aircraft, around a tenth of what Germany’s Luftwaffe fielded. And the aircraft the U.S. did have were out of date: Though the airplane was invented in the U.S. in 1903, by the late 1930s the most advanced aircraft were being produced in other countries, and there was little urgency to close this gap. Military orders for Boeing’s advanced B-17, of which more than 12,000 would ultimately be built, were canceled in 1937 after a crash during testing in favor of the cheaper and less capable B-18, nearly driving Boeing into bankruptcy.

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the spoken word - from 1888

christmas lights

Our family had a string of the NOMA bubble lites .  They didn't last very long.

 

 

veritasium on glass

if you need a hobby

thirty years!

This is the original holiday card I sketched back in 1994 along with a bit of midi.  I posted it to the then-new web and the few people I knew with browsers on their machines gave a thumbs up.  The next year a bit of laziness saw  it going out unchanged.   The third year came and I almost forgot, only to be reminded by a few dozen requests that came just before Christmas. From then on I posted it every year soon after Thanksgiving.  When the 25th anniversary rolled around a few years ago,   I asked if people wanted something new, but the unanimous vote was for the  classic.  

 

Autoplay didn’t exist then so you’ll have to start the music yourself on the like below the main image.

Happy Holidays! - peace, friendship, and health!

http://tingilinde.typepad.com/starstuff/good-yule.html

 

on the history of industrial labs

A very high level look, but perhaps interesting.

Probably way too high level for refugees