91
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-pu...
Ken Shirriff
Computer history, restoring vintage computers, IC reverse engineering, and whatever
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92
Repairing a 1960s mainframe: Fixing the IBM 1401's core memory and power supply
A few weeks ago, I wanted to use one of the vintage IBM 1401 mainframe computers at the Computer History Museum, but the computer wasn't wor...
93
A one-bit processor explained: reverse-engineering the vintage MC14500B
The Motorola MC14500B 1 is a 1-bit processor introduced in 1976. While a 1-bit processor might seem almost useless, 2 it was marketed as...
94
Reverse-engineering the conditional jump circuitry in the 8086 processor
Intel introduced the 8086 microprocessor in 1978 and it had a huge influence on computing. I'm reverse-engineering the 8086 by examining t...
95
How the Z80's registers are implemented
The 8-bit Z80 microprocessor is famed for use in many early personal computers such the Osborne 1, TRS-80, and Sinclair ZX Spectrum. The Z80...
96
Yamaha DX7 reverse-engineering, part III: Inside the log-sine ROM
The Yamaha DX7 digital synthesizer (1983) was the classic synthesizer for 1980s pop music. It used two custom digital chips to generate so...
97
Inside a Ferroelectric RAM Chip
Ferroelectric memory (FRAM) is an interesting storage technique that stores bits in a special "ferroelectric" material. Ferroelectric memory...
98
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 copro...
99
Repairing the card reader for a 1960s mainframe: cams, relays and a clutch
I recently helped repair the card reader for the Computer History Museum's vintage IBM 1401 mainframe. In the process, I learned a lot abou...
100
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...
101
Fixing the Ethernet Board from a Vintage Xerox Alto
A Xerox Alto system on the East coast had Ethernet problems, so the owner sent me the Ethernet board to diagnose. (After restoring our Alto,...
102
An 8-tube module from a 1954 IBM 705 mainframe: it's a key debouncer
IBM's vacuum tube computers of the 1950s were built from pluggable modules, each holding eight tubes and the associated components. I recent...
103
Reverse-engineering a vintage power supply chip from die photos
I recently did a PC power supply teardown so I figured it would be interesting to go deeper and see what happens inside the power supply'...
104
Why the Z-80's data pins are scrambled
If you look closely at the datasheet for a Z-80 chip, you'll notice the data pins are in a random-looking order. The address pins (A) are ni...
105
Teardown of a quartz crystal oscillator and the tiny IC inside
The quartz oscillator is an important electronic circuit, providing highly-accurate timing signals at a low cost. A quartz crystal has the...
106
A look inside the chips that powered the landmark Polaroid SX-70 instant camera
The revolutionary Polaroid SX-70 1 camera (1972) was a marvel of engineering: the world's first instant SLR camera. This iconic camera wa...
107
Tracing the roots of the 8086 instruction set to the Datapoint 2200 minicomputer
The Intel 8086 processor started the x86 architecture that is still extensively used today. The 8086 has some quirky characteristics: it i...
108
Reverse engineering the 76477 “Space Invaders” sound chip from die photos (2017)
Remember the old video game Space Invaders? Some of its sound effects were provided by a chip called the 76477 Complex Sound Generation ch...
109
Inside the HP Nanoprocessor
The Nanoprocessor is a mostly-forgotten processor developed by Hewlett-Packard in 1974 1 as a microcontroller 2 for their products. Stra...
110
Examining circuit boards from the Space Shuttle's I/O Processor
The Space Shuttle's five 1 general-purpose computers played a critical role in each flight: controlling the engines, monitoring thousands o...
111
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...
112
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-generati...
113
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 experiment...
114
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 main...
115
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...
116
Glowing mercury thyratrons: inside a 1940s Teletype switching power supply
We recently started restoring a Teletype Model 19, a Navy communication system introduced in the 1940s. 14 This Teletype was powered by a b...
117
The digital ranging system that measured the distance to the Apollo spacecraft
During the Apollo missions to the Moon, a critical task for NASA was determining the spacecraft's position. To accomplish this, they devel...
118
The printer that wouldn't print: Fixing an IBM 1401 mainframe from the 1960s
The Computer History Museum has two operational IBM 1401 computers used for demos , but a few weeks ago one computer suddenly couldn't prin...
119
Inside the 8086 processor, tiny charge pumps create a negative voltage
Introduced in 1978, the revolutionary Intel 8086 microprocessor led to the x86 processors used in most desktop and server computing today....
120
Restoring Y Combinator's Xerox Alto, day 3: Inside the disk drive
I'm helping restore a Xerox Alto — a legendary minicomputer from 1973 that helped set the direction for personal computing. This post desc...