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The Intel 8088 processor's instruction prefetch circuitry: a look inside
In 1979, Intel introduced the 8088 microprocessor, a variant of the 16-bit 8086 processor. IBM's decision to use the 8088 processor in the IBM PC (1981) was a critical point in computer history,...
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Inside an unusual 7400-series chip implemented with a gate array
When I look inside a chip from the popular 7400 series, I know what to expect: a fairly simple die, implemented in a straightforward, cost-effective way. However, when I looked inside a military-grade...
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Talking to memory: Inside the Intel 8088 processor's bus interface state machine
In 1979, Intel introduced the 8088 microprocessor, a variant of the 16-bit 8086 processor. IBM's decision to use the 8088 processor in the IBM PC (1981) was a critical point in computer history,...
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Inside a vintage aerospace navigation computer of uncertain purpose
I recently obtained an aerospace computer from the early 1970s, apparently part of a navigation system. Aerospace computers are an interesting but mostly neglected area of computer hardware, so I'm...
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Inside the tiny chip that powers Montreal subway tickets
To use the Montreal subway (the Métro), you tap a paper ticket against the turnstile and it opens. The ticket works through a system called NFC, but what's happening internally? How does the ticket...
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Standard cells: Looking at individual gates in the Pentium processor
Intel released the powerful Pentium processor in 1993, a chip to "separate the really power-hungry folks from ordinary mortals." The original Pentium was followed by the Pentium Pro, the Pentium II,...
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Inside an IBM/Motorola mainframe controller chip from 1981
In this article, I look inside a chip in the IBM 3274 Control Unit.1 But before I discuss the chip, I need to give some background on mainframes. (I didn't completely analyze the chip, so don't expect...
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Reverse engineering the 59-pound printer onboard the Space Shuttle
The Space Shuttle contained a bulky printer so the astronauts could receive procedures, mission plans, weather reports, crew activity plans, and other documents. Needed for the first Shuttle launch in...
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Inside the guidance system and computer of the Minuteman III nuclear missile
The Minuteman missile was introduced in 1962 as a key part of America's nuclear deterrent. The Minuteman III missile is currently the only US land-based intercontinental ballistic missile (ICBM), with...
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The Pentium as a Navajo weaving
Hurrying through the National Gallery of Art five minutes before closing, I passed a Navajo weaving with a complex abstract pattern. Suddenly, I realized the pattern was strangely familiar, so I...
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Inside a ferroelectric RAM chip
Ferroelectric memory (FRAM) is an interesting storage technique that stores bits in a special "ferroelectric" material. Ferroelectric memory is nonvolatile like flash memory, able to hold its data for...
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Reverse-engineering a three-axis attitude indicator from the F-4 fighter plane
We recently received an attitude indicator for the F-4 fighter plane, an instrument that uses a rotating ball to show the aircraft's orientation and direction. In a normal aircraft, the artificial...
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Wealth distribution in the United States
Forbes recently published the Forbes 400 List for 2024, listing the 400 richest people in the United States. This inspired me to make a histogram to show the distribution of wealth in the United...
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Antenna diodes in the Pentium processor
I was studying the silicon die of the Pentium processor and noticed some puzzling structures where signal lines were connected to the silicon substrate for no apparent reason. Two examples are in the...
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Intel's $475 million error: the silicon behind the Pentium division bug
In 1993, Intel released the high-performance Pentium processor, the start of the long-running Pentium line. The Pentium had many improvements over the previous processor, the Intel 486, including a...
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Pi in the Pentium: reverse-engineering the constants in its floating-point unit
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...
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The origin of the cargo cult metaphor
The cargo cult metaphor is commonly used by programmers. This metaphor was popularized by Richard Feynman's "cargo cult science" talk with a vivid description of South Seas cargo cults. However, this...
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Reverse-engineering a carry-lookahead adder in the Pentium
Addition is harder than you'd expect, at least for a computer. Computers use multiple types of adder circuits with different tradeoffs of size versus speed. In this article, I reverse-engineer an 8-bit...
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Interesting BiCMOS circuits in the Pentium, reverse-engineered
Intel released the powerful Pentium processor in 1993, establishing a long-running brand of processors. Earlier, I wrote about the ROM in the Pentium's floating point unit that holds constants such as...
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The origin and unexpected evolution of the word "mainframe"
What is the origin of the word "mainframe", referring to a large, complex computer? Most sources agree that the term is related to the frames that held early computers, but the details are vague.1 It...
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The Pentium contains a complicated circuit to multiply by three
In 1993, Intel released the high-performance Pentium processor, the start of the long-running Pentium line. I've been examining the Pentium's circuitry in detail and I came across a circuit to multiply...
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A USB interface to the "Mother of All Demos" keyset
In the early 1960s, Douglas Engelbart started investigating how computers could augment human intelligence: "If, in your office, you as an intellectual worker were supplied with a computer display...
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Notes on the Pentium's microcode circuitry
Most people think of machine instructions as the fundamental steps that a computer performs. However, many processors have another layer of software underneath: microcode. With microcode, instead of...
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A tricky Commodore PET repair: tracking down 6 1/2 bad chips
.cite { font-size: 70%;} .ref { vertical-align: super; font-size: 60%;} code {font-size: 100%; font-family: courier, fixed;} In 1977, Commodore released the PET computer, a quirky home computer that...
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The absurdly complicated circuitry for the 386 processor's registers
The groundbreaking Intel 386 processor (1985) was the first 32-bit processor in the x86 architecture. Like most processors, the 386 contains numerous registers; registers are a key part of a processor...
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