91
Reverse-engineering the 8086 processor's address and data pin circuits
The Intel 8086 microprocessor (1978) started the x86 architecture that continues to this day. In this blog post, I'm focusing on a small p...
Ken Shirriff
Computer history, restoring vintage computers, IC reverse engineering, and whatever
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Visit righto.com → RSS feedOn Hacker News Jul 2013 – Oct 2026
Hardware & Electronics 171History & Retro Computing 128Systems & Performance 21Software Engineering 10Crypto & Blockchain 9Security & Privacy 7
92
The Z-80 has a 4-bit ALU. Here's how it works.
The 8-bit Z-80 processor is famed for use in many early personal computers such the Osborne 1, TRS-80, and Sinclair ZX Spectrum, and it is s...
93
The complex history of the Intel i960 RISC processor
The Intel i960 was a remarkable 32-bit processor of the 1990s with a confusing set of versions. Although it is now mostly forgotten (outs...
94
Reverse engineering the ARM1, ancestor of the iPhone's processor
Almost every smartphone uses a processor based on the ARM1 chip created in 1985. The Visual ARM1 simulator shows what happens inside the...
95
Inside the 74181 ALU chip
What's inside a TTL chip? To find out, I opened up a 74181 ALU chip, took high-resolution die photos, and reverse-engineered the chip. 1 In...
96
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 exper...
97
The Texas Instruments TMX 1795: the first, forgotten microprocessor
The first 8-bit microprocessor, the TMX 1795 had the same architecture as the 8008 but was built months before the 8008. Never sold commerci...
98
Examining the core memory module inside a vintage IBM 1401 mainframe
The IBM 1401 mainframe computer was announced in 1959 and by the mid-1960s had become the best-selling computer , extremely popular with me...
99
Die analysis of the 8087 math coprocessor's fast bit shifter
Floating-point numbers are very useful for scientific programming, but early microprocessors only supported integers directly. 1 Although...
100
Soyuz spacecraft digital clock teardown
We recently obtained a clock that flew on a Soyuz space mission. 1 The clock, manufactured in 1984, is much more complex inside than you'd ...
101
Die shrink: How Intel scaled down the 8086 processor
The revolutionary Intel 8086 microprocessor was introduced 42 years ago this month so I've been studying its die. 1 I came across two 8...
102
Reverse-engineering an unusual IBM modem board from 1965
The vintage IBM circuit board below has a large metal block on it that caught my attention, so I investigated it in detail. It turns out t...
103
IBM, sonic delay lines, and the history of the 80×24 display
What explains the popularity of terminals with 80×24 and 80×25 displays? A recent blog post " 80x25 " motivated me to investigate this. The ...
104
X-ray reverse-engineering a hybrid module from 1960s Apollo test equipment
In this blog post, I reverse-engineer a hybrid module that was used for ground-testing of equipment from the Apollo space program. But fir...
105
Restoring YC's Xerox Alto, day 1: Power supplies and disk interface
A few days ago, I wrote about how I'm helping restore a Xerox Alto for Y Combinator. This new post describes the first day of restoration...
106
Restoring YC's Xerox Alto day 9: tracing a crash through software and hardware
Last week, after months of restoration, we finally got the vintage Xerox Alto computer to boot ( details ) and run programs. However, so...
107
Reverse-engineering precision op amps from a 1969 analog computer
We are restoring a vintage 1 computer that CuriousMarc recently obtained. Analog computers were formerly popular for fast scientific compu...
108
Christmas shopping the IBM way: computerized gift selection in 1962
In 1962, the Simpson's department store in Toronto used an IBM computer to help customers select Christmas gifts, based on the characteris...
109
A database of SMS cards: The technology inside IBM's 1960s mainframes
IBM's mainframes of the 1960s are based on an interesting technology - Standard Modular System cards or SMS cards. These cards, created in ...
110
The unusual bootstrap drivers inside the 8086 microprocessor chip
The 8086 microprocessor is one of the most important chips ever created; it started the x86 architecture that still dominates desktop and ...
111
Reverse-engineering a mysterious Univac computer board
The IBM 1401 team at the Computer History Museum accumulates a lot of mystery components from donations and other sources. While going thr...
112
Restoring Y Combinator's Xerox Alto, day 2: Repairing the display
This post describes how we repaired the monitor from a Xerox Alto. The Alto was a revolutionary computer, designed in 1973 at Xerox PARC ...
113
Silicon die analysis: inside an op amp with interesting “butterfly” transistors
Some integrated circuits have very interesting dies under a microscope, like the chip below with designs that look kind of like butterflies....
114
A look at IBM S/360 core memory: In the 1960s, 128 kilobytes weighed 610 pounds
I recently received a vintage core memory array, part of an IBM System/360 mainframe computer. These arrays were used in a 128-kilobyte core...
115
The Apple-1's unusual MOS clock driver chip
Apple's first product was the Apple-1 computer, introduced in 1976. This early microcomputer used an unusual type of storage for its disp...
116
Booting the IBM 1401: How a 1959 punch-card computer loads a program
How do you boot a computer from punch cards when the computer has no operating system and no ROM? To make things worse, this computer req...
117
"Special register groups" invaded computer dictionaries for decades (2019)
Half a century ago, the puzzling phrase "special register groups" started showing up in definitions of "CPU", and it is still there. In this...
118
Reverse-engineering an airspeed/Mach indicator from 1977
How does a vintage airspeed indicator work? CuriousMarc picked one up for a project, but it didn't have any documentation, so I reverse-en...
119
IBM paperweight teardown: Reverse-engineering 1970s memory chips
I recently received a vintage IBM paperweight from the early 1970s that showcases some memory chips. 1 When IBM started using integrated ...
120
Talking with the Moon: Inside Apollo's premodulation processor
The Apollo missions to the Moon required complex hardware to communicate between Earth and the spacecraft, sending radio signals over hund...