Op amp on the Moon: Reverse-engineering a hybrid op amp module

Ken Shirriff has written an article on reverse engineering a hybrid op amp module: I recently obtained a mysterious electronic component in a metal can, flatter and slightly larger than a typical integrated circuit.1 After opening it up and reverse engineering the circuit, I determined that this was an op amp built for NASA in […]

Two bits per transistor: high-density ROM in Intel’s 8087 floating point chip

Ken Shirriff has a great write-up about the multi-level ROM in Intel’s 8087 floating point chip: The 8087 chip provided fast floating point arithmetic for the original IBM PC and became part of the x86 architecture used today. One unusual feature of the 8087 is it contained a multi-level ROM (Read-Only Memory) that stored two […]

Sega System 16 security reverse engineering

Reverse engineering of Sega’s System 16 Hitachi FD1089 cpu security module by Eduardo Cruz: I’m glad to announce the successful reverse engineering of Sega’s System 16 cpu security modules. This development will enable collectors worldwide preserving hardware unmodified, and stop the general discarding of Hitachi FD modules. The project is right now involving external testers so […]

A journey into Capcom’s CPS2 silicon – part 3

Eduardo Cruz published the third and last post in the Capcom CPS2 reverse engineering series we covered previously: For many years, finding how and where did Capcom hid away its security implementation has been a pending critical task for the arcade community. CPS2 systems running out of battery were rendered useless forcing collectors worldwide to […]

Inside the 76477 space invaders sound effect chip: Digital logic implemented with I2L

Ken Shirriff has written an excellent in-depth look at the 76477 sound effects chip: The 76477 Complex Sound Generation chip (1978) provided sound effects for Space Invaders1 and many other video games. It was also a popular hobbyist chip, easy to experiment with and available at Radio Shack. I reverse-engineered the chip from die photos […]

Repairing the card reader for a 1960s mainframe: cams, relays and a clutch

Ken Shirriff writes: I recently helped repair the card reader for the Computer History Museum’s vintage IBM 1401 mainframe. In the process, I learned a lot about the archaic but interesting electromechanical systems used in the card reader. Most of the card reader is mechanical, with belts, gears, and clutches controlling the movement of cards […]

IBM mainframe tube module part II: Powering up and using a 1950s key debouncer

Here’s an interesting two-part series of posts by Ken Shirriff detailing the IBM mainframe tube module. Part 1 discuss the tube modules and describe the IBM 705 that used this module. Part 2 covers powering up the module and getting it to work. Read the full post at Ken Shirriff’ blog.

A journey into Capcom’s CPS2 silicon – Part 2

Here’s an informative part 2 of the Capcom CPS2 reverse engineering series by Eduardo Cruz: Capcom’s Play System 2, also known as CPS2, was a new arcade platform introduced in 1993 and a firm call on bootlegging. Featuring similar but improved specs to its predecessor CPS1, the system introduced a new security architecture that gave Capcom for […]

Reverse engineering of BK Precision 1696 switching power supply’s LCD protocol

Kerry Wong writes: As mentioned in my previous post, besides the broken LCD there was also an issue with the power supply portion of the unit and the output voltage was clamped at around 10 to 11V. The digital circuitry portion however seemed to be intact. Unfortunately since an identical LCD is virtually unobtanium, I […]

Examining a vintage RAM chip, I find a counterfeit with an entirely different die inside

Ken Shirriff writes, “A die photo of a vintage 64-bit TTL RAM chip came up on Twitter recently, but the more I examined the photo the more puzzled I became. The chip didn’t look at all like a RAM chip or even a TTL chip, and in fact appeared partially analog. By studying the chip’s […]

A look inside the DS3231 real-time clock

Pete posted an article taking a closer look at Maxim’s DS3231 real-time clock: Fortunately, Maxim also offers the DS3231, which is advertised as an “Extremely Accurate I2C-Integrated RTC/TCXO/Crystal”. This chip has the 32kHz crystal integrated into the package itself and uses a built-in temperature sensor to periodically measure the temperature of the crystal and, by […]

Inside Intel’s first product: the 3101 RAM chip held just 64 bits

Ken Shirriff writes: Intel’s first product was not a processor, but a memory chip: the 31011 RAM chip, released in April 1969. This chip held just 64 bits of data (equivalent to 8 letters or 16 digits) and had the steep price tag of $99.50.2 The chip’s capacity was way too small to replace core […]

Reverse engineering the 76477 “Space Invaders” sound effect chip from die photos

Ken Shirriff has written an article on reverse engineering the 76477 “Space Invaders” sound effect chip: Remember the old video game Space Invaders? Some of its sound effects were provided by a chip called the 76477 Complex Sound Generation chip. While the sound effects1 produced by this 1978 chip seem primitive today, it was used […]

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 […]

Inside the 74181 ALU chip: die photos and reverse engineering

A detailed die photos and reverse engineering of the 74181 ALU chip by Ken Shirriff: 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 Inside I found several types of gates, implemented with interesting circuitry and unusual transistors. The 74181 was a […]

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 […]