Inside The F-4 Attitude Indicator

[Ken] recently obtained an attitude indicator—sometimes called an artificial horizon—from an F-4 fighter jet. Unlike some indicators, the F-4’s can rotate to show pitch, roll, and yaw, so it …

[Ken] Looks At The 386

The 80386 was — arguably — Intel’s first modern CPU. The 8086 was commercially successful, but the paged memory model was stifling. The 80286 also had a protected mode, which diff…

16 Kbit DRAM Gives Up Its Secrets

[Ken Shirriff] is looking inside chips again. This time, the subject is the MK4116 — a 16 Kbit DRAM chip. Even without a calculator, you know that’s a whopping 2 Kbytes, and while that …

Finding Undocumented 8086 Instructions Via Microcode

Video gamers know about cheat codes, but assembly language programmers are often in search of undocumented instructions. One way to find them is to map out all of a CPU’s opcodes and where th…

String Operations The Hard(ware) Way

One of the interesting features of the 8086 back in 1978 was the provision for “string” instructions. These took the form of prefixes that would repeat the next instruction a certain nu…

Silicon Sleuthing: Finding A Ancient Bugfix On The 8086

Few CPUs have had the long-lasting influence that the 8086 did. It is hard to believe that when your modern desktop computer boots, it probably thinks it is an 8086 from 1978 until some software go…

Exploring Texas Instrument’s Forgotten CPU

Texas Instruments isn’t the name you usually hear associated with the first microprocessor. But the TI TMX 1795 was an 8008 chip produced months before the 8008. It was never available commer…

The MOS 7600 Video Game Chip Gives Up Its Secrets

A good chip decapping and reverse engineering is always going to capture our interest, and when it comes from [Ken Shirriff] we know it’s going to be a particularly good one. This time he&#82…

Can You Hear Me Now? Lunar Edition

Despite what it looks like in the movies, it is hard to communicate with astronauts from Earth. There are delays, and space vehicles don’t usually have a lot of excess power. Plus everything …

The Apollo Digital Ranging System: More Than Meets The Eye

If you haven’t seen [Ken Shirriff]’s teardowns and reverse engineering expeditions, then you’re in for a treat. His explanation and demonstration of the Apollo digital ranging sys…

[Ken Shirriff] Takes A Bite Of The Apple-I

The Apple-I was a far cry from Apple’s later products. A $666 single-board computer, the product had some unique design features including using a shift register for video memory to save mone…

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...

Yamaha DX7 chip reverse-engineering, part V: the output circuitry

The Yamaha DX7 digital synthesizer (1983) was the classic synthesizer in 1980s pop music. It uses a technique called FM synthesis to produ...

Silicon die teardown: a look inside an early 555 timer chip

If you've played around with electronic circuits, you probably know the 555 timer integrated circuit, 1 said to be the world's best-selli...

Simulating the IBM 360/50 mainframe from its microcode

The IBM System/360 was a groundbreaking family of mainframe computers announced on April 7, 1964. System/360 was an extremely risky "bet-t...

Reverse-engineering a tiny 1980s chip that plays Christmas tunes

For the holidays, I decapped a chip that plays three Christmas melodies. The UM66T melody chip from the 1980s was designed for application...

A Particularly Festive Chip Decapping

As we approach the moment in the year at which websites enter a festive silly season of scrambling to find any story with a festive angle, we’re pleased to see the ever-reliable [Ken Shirriff…

Yamaha DX7 chip reverse-engineering, part 4: how algorithms are implemented

The Yamaha DX7 digital synthesizer (1983) was the classic synthesizer in 1980s pop music. It uses two custom digital chips to generate sou...

Apollo Shift Register Is Discrete

We’re unabashed fans of [Ken Shirriff] here at Hackaday, and his latest post about an Apollo-era transistorized shift register doesn’t disappoint. Of course, nowadays a 16-bit shift reg…