121
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...
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
122
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...
123
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...
124
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...
125
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...
126
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...
127
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...
128
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...
129
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...
130
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...
131
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...
132
How I added 6 characters to Unicode (and you can too)
Edit (June 2018): Unicode 11 is released, containing the half stars. Now the wait for font support... Star characters (☆★) have long b...
133
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...
134
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....
135
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...
136
Reverse-engineering the first FPGA chip, the XC2064
A Field-Programmable Gate Array (FPGA) can implement arbitrary digital logic, anything from a microprocessor to a video generator or crypt...
137
The Intel 8087 chip: floating-point addition and subtraction
In 1980, Intel introduced the 8087, a chip that made floating-point operations much faster in the IBM PC and other systems. Although the 808...
138
Inside the 8086 processor's instruction prefetch circuitry
The groundbreaking 8086 microprocessor was introduced by Intel in 1978 and led to the x86 architecture that still dominates desktop and se...
139
Reverse-engineering the division microcode in the Intel 8086 processor
While programmers today take division for granted, most microprocessors in the 1970s could only add and subtract — division required a sl...
140
A computer built from NOR gates: inside the Apollo Guidance Computer
We recently restored an Apollo Guidance Computer 1 , the computer that provided guidance, navigation, and control onboard the Apollo flight...
141
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...
142
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...
143
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...
144
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...
145
Reverse-engineering the Intel 8087's tangent algorithm: more than CORDIC
I hope you're not tired of the 8087, because I have another article about Intel's floating-point chip. 1 In 1980, Intel introduced the 8087...
146
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...
147
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...
148
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...
149
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...
150
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...