Ken Shirriff's Blog
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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...
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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,...
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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...
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The first microcomputer: The transfluxor-powered Arma Micro Computer from 1962
What would you say is the first microcomputer? 1 The Apple I from 1976? The Altair 8800 from 1974? Perhaps the lesser-known Micral N (1973) or...
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Inside the mechanical Bendix Air Data Computer, part 5: motor/tachometers
The Bendix Central Air Data Computer (CADC) is an electromechanical analog computer that uses gears and cams for its mathematics. It was a key part...
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Reverse-engineering an analog Bendix air data computer: part 4, the Mach section
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Reverse engineering standard cell logic in the Intel 386 processor
The 386 processor (1985) was Intel's most complex processor at the time, with 285,000 transistors. Intel had scheduled 50 person-years to design...
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Reverse engineering CMOS, illustrated with a vintage Soviet counter chip
I recently came across an interesting die photo of a Soviet 1 chip, probably designed in the 1970s. This article provides an introductory guide...
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Inside the mechanical Bendix Air Data Computer, part 3: pressure transducers
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Interesting double-poly latches inside AMD's vintage LANCE Ethernet chip
I've studied a lot of chips from the 1970s and 1980s, so I usually know what to expect. But an Ethernet chip from 1982 had something new: a...
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The transparent chip inside a vintage Hewlett-Packard floppy drive
While repairing an eight-inch HP floppy drive, we found that the problem was a broken interface chip. Since the chip was bad, I decapped it and...
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Two interesting XOR circuits inside the Intel 386 processor
Intel's 386 processor (1985) was an important advance in the x86 architecture, not only moving to a 32-bit processor but also switching to a CMOS...
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Reverse engineering the barrel shifter circuit on the Intel 386 processor die
The Intel 386 processor (1985) was a large step from the 286 processor, moving x86 to a 32-bit architecture. The 386 also dramatically improved...
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Inside the Intel 386 processor die: the clock circuit
Processors are driven by a clock, which controls the timing of each step inside the chip. In this blog post, I'll examine the clock-generation...
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Reverse engineering the Intel 386 processor's register cell
The groundbreaking Intel 386 processor (1985) was the first 32-bit processor in the x86 line. It has numerous internal registers: general-purpose...