Inside the vintage 74181 ALU chip: how it works and why it’s so strange

Ken Shirriff writes: The 74181 ALU (arithmetic/logic unit) chip powered many of the minicomputers of the 1970s: it provided fast 4-bit arithmetic and logic functions, and could be combined to handle larger words, making it a key part of many CPUs. But if you look at the chip more closely, there are a few mysteries. […]

Analyzing the vintage 8008 processor from die photos: its unusual counters

Ken Shirriff writes: The revolutionary Intel 8008 microprocessor is 45 years old today (March 13, 2017), so I figured it’s time for a blog post on reverse-engineering its internal circuits. One of the interesting things about old computers is how they implemented things in unexpected ways, and the 8008 is no exception. Compared to modern […]

Reverse-engineering the surprisingly advanced ALU of the 8008 microprocessor

Ken Shirriff has written an article on reverse engineering the ALU of the 8008 microprocessor: A computer’s arithmetic-logic unit (ALU) is the heart of the processor, performing arithmetic and logic operations on data. If you’ve studied digital logic, you’ve probably learned how to combine simple binary adder circuits to build an ALU. However, the 8008’s […]

Die photos and analysis of the revolutionary 8008 microprocessor, 45 years old

Ken Shirriff has written an article detailing die photos of the vintage Intel 8008 that reveal the circuitry it used: Intel’s groundbreaking 8008 microprocessor was first produced 45 years ago.1 This chip, Intel’s first 8-bit microprocessor, is the ancestor of the x86 processor family that you may be using right now. I couldn’t find good […]

Inside a RFID race timing chip: die photos of the Monza R6

Ken Shirriff took some die photos of the Monza R6 chip  and wrote a post on his blog on how the RFID timing chip works: I recently watched a cross-country running race that used a digital timing system, so I investigated how the RFID timing chip works. Each runner wears a race bib like the […]

Reverse engineering a server CPU voltage regulator module

Andy Brown wrote an article on reverse engineering a CPU voltage regulator: A recent ebay fishing expedition yielded an interesting little part for the very reasonable sum of about five pounds. It’s a voltage regulator module from a Dell PowerEdge 6650 Xeon server. I originally bought this because I had the idea of salvaging parts […]

Nevo C2 remote control – Reverse engineering, part 1

Reverse engineering of a Nevo C2 remote control from Most recently I’ve switched to the “Nevo C2” remotes (also known as “Xsight Color” or “ARRX15G”), which have a graphical display built in. This makes it easy for me to deal with the huge array (TiVo, HTPC, plus eleven game consoles) of devices I’ve got hooked […]

Counting bits in hardware: Reverse engineering the silicon in the ARM1 processor

Ken Shirriff writes: How can you count bits in hardware? In this article, I reverse-engineer the circuit used by the ARM1 processor to count the number of set bits in a 16-bit field, showing how individual transistors form multiplexers, which are combined into adders, and finally form the bit counter. The ARM1 is the ancestor […]

Reverse engineering the ARM1, ancestor of the iPhone’s processor

Another great article from Ken Shirriff, this time on reverse engineering the ARM1: Almost every smartphone uses a processor based on the ARM1 chip created in 1985. The Visual ARM1 simulator shows what happens inside the ARM1 chip as it runs; the result (below) is fascinating but mysterious.[1] In this article, I reverse engineer key […]

Reverse engineering the ESP8266 WIFI-to-Serial port adapter

Here’s a video from electronupdate on reverse engineering the ESP8266 WIFI-to-Serial port adapter: Another very interesting bit of technology. The combination of so much functionality into such a small part is a real touch-stone as to where things are heading. A quick look at the antenna design to see if I could sort down the […]

Macbook charger teardown: The surprising complexity inside Apple’s power adapter

A teardown of a Macbook charger by Ken Shirriff: Have you ever wondered what’s inside your Macbook’s charger? There’s a lot more circuitry crammed into the compact power adapter than you’d expect, including a microprocessor. This charger teardown looks at the numerous components in the charger and explains how they work together to power your laptop. […]

Understanding silicon circuits: inside the ubiquitous 741 op amp

Ken Shirriff’s writes, “The 741 op amp is one of the most famous and popular ICs with hundreds of millions sold since its invention in 1968 by famous IC designer Dave Fullagar. In this article, I look at the silicon die for the 741, discuss how it works, and explain how circuits are built from […]

Schlumberger 4002 signal generator

Mario wrote an article on reverse engineering a Schlumberger 4002 signal generator: What I got was a Schlumberger 4002 signal generator. It ranges from 0.1 to 2160 MHz with 10-20 Hz tuning accuracy, selectable output amplitude from -138.9 dBm up to +13 dBm in 0.1 dB steps, auto-sweeping and several extras like an OCXO for stability, 20 dB […]

Examining the core memory module inside a vintage IBM 1401 mainframe

Ken Shirriff writes: The IBM 1401 mainframe computer was announced in 1959 and by the mid-1960s had become the best-selling computer, extremely popular with medium and large businesses because of its low cost. A key component of the 1401’s success was its 4,000 character core memory, which stored data on tiny magnetized rings called cores. […]

Inside the Intel 1405: die photos of a shift register memory from 1970

Ken writes: In the Datapoint 2200, each memory board had 32 shift registers, providing 2K of storage. The processor board used a counter to keep track of the shift register position, and would stop processing until the right bits were available. (Kind of like a cache miss in modern processors.) I got a display board from […]

Reverse engineering a Verisure wireless alarm

Here’s an informative two-part series of posts over at FunOverIP detailing how to reverse engineer a Verisure wireless alarm. Part 1 details the beginning steps such as finding the modules radio frequency and modulation type, analyzing the chipset datasheet and using GNU Radio.