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Microcode in Intel's 8087 floating-point chip: the scale instruction
In the 1970s, floating-point arithmetic was a mess. Computer manufacturers had a dozen incompatible arithmetic standards. Moreover, floating-point systems were designed around hardware simplicity...
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Cores in space: The core memory module from a 1980 Spacelab computer
Spacelab was a reusable laboratory that could be carried in the Space Shuttle's cargo bay, providing lab space for astronauts and experiments.1 Because Spacelab was a European project, it used a...
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Energizing a vacuum-tube flip-flop module from a 1948 IBM system
In 1948, IBM introduced the 604 Electronic Calculating Punch. This machine was a programmable calculator, about the size of a double refrigerator. It was not quite a computer, but was programmed by...
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Examining circuit boards from the Space Shuttle's I/O Processor
The Space Shuttle's five1 general-purpose computers played a critical role in each flight: controlling the engines, monitoring thousands of sensors, displaying data to the astronauts, and navigating...
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The adder at the heart of Intel's 8087 floating-point chip
In 1980, Intel released the Intel 8087 floating-point coprocessor, a chip that could make math up to 100 times faster. As well as arithmetic and square roots, the 8087 computed transcendental functions...
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Powering up a module from the IBM 604: an electronic calculator from 1948
1948 was an interesting time for computing. For decades, businesses had used punch card equipment that added and sorted electromechanically. Now these electromechanical relays and counting wheels were...
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Microcode inside the Intel 8087 floating-point chip: register exchange
In 1980, Intel introduced the 8087 floating-point chip, a co-processor that made floating-point operations up to 100 times faster. This chip was highly influential, and today most processors use the...
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Reverse engineering circuitry in a Spacelab computer from 1980
Spacelab was a reusable laboratory that could be carried in the cargo bay of the Space Shuttle, providing lab space for astronauts and experiments. Spacelab was controlled by a French-built...
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The electromechanical angle computer inside the B-52 bomber's star tracker
Before GPS, how did aircraft navigate? One important technique was celestial navigation: navigating from the positions of the stars, planets, or the sun. While celestial navigation is accurate, cannot...
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The rise and fall of IBM's 4 Pi aerospace computers: an illustrated history
The morning of April 12, 1981, 20 years to the day after Yuri Gagarin became the first person in space, the Space Shuttle thundered into the Florida sky. Commander Young and Pilot Crippen were at the...
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Instruction decoding in the Intel 8087 floating-point chip
pre {border:none;} In the 1980s, if you wanted your IBM PC to run faster, you could buy the Intel 8087 floating-point coprocessor chip. With this chip, CAD software, spreadsheets, flight simulators,...
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Notes on the Intel 8086 processor's arithmetic-logic unit
In 1978, Intel introduced the 8086 processor, a revolutionary chip that led to the modern x86 architecture. Unlike modern 64-bit processors, however, the 8086 is a 16-bit chip. Its arithmetic/logic...
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Conditions in the Intel 8087 floating-point chip's microcode
In the 1980s, if you wanted your computer to do floating-point calculations faster, you could buy the Intel 8087 floating-point coprocessor chip. Plugging it into your IBM PC would make operations up...
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The stack circuitry of the Intel 8087 floating point chip, reverse-engineered
Early microprocessors were very slow when operating with floating-point numbers. But in 1980, Intel introduced the 8087 floating-point coprocessor, performing floating-point operations up to 100 times...
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Unusual circuits in the Intel 386's standard cell logic
I've been studying the standard cell circuitry in the Intel 386 processor recently. The 386, introduced in 1985, was Intel's most complex processor at the time, containing 285,000 transistors. Intel's...
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Solving the NYTimes Pips puzzle with a constraint solver
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A Navajo weaving of an integrated circuit: the 555 timer
The noted Diné (Navajo) weaver Marilou Schultz recently completed an intricate weaving composed of thick white lines on a black background, punctuated with reddish-orange diamonds. Although this...
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Why do people keep writing about the imaginary compound Cr2Gr2Te6?
I was reading the latest issue of the journal Science, and a paper mentioned the compound Cr2Gr2Te6. For a moment, I thought my knowledge of the periodic table was slipping, since I couldn't remember...
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Here be dragons: Preventing static damage, latchup, and metastability in the 386
I've been reverse-engineering the Intel 386 processor (from 1985), and I've come across some interesting circuits for the chip's input/output (I/O) pins. Since these pins communicate with the outside...
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A CT scanner reveals surprises inside the 386 processor's ceramic package
Intel released the 386 processor in 1985, the first 32-bit chip in the x86 line. This chip was packaged in a ceramic square with 132 gold-plated pins protruding from the underside, fitting into a...
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