Extracting ROM constants from the 8087 math coprocessor’s die

Ken posted an article taking a closer look at Intel 8087 chip: Intel introduced the 8087 chip in 1980 to improve floating-point performance on the 8086 and 8088 processors, and it was used with the original IBM PC. Since early microprocessors operated only on integers, arithmetic with floating-point numbers was slow and transcendental operations such […]

Tiny transformer inside: Decapping an isolated power transfer chip

Ken Shirriff writes: I saw an ad for a tiny chip1 that provides 5 volts2 of isolated power: You feed 5 volts in one side, and get 5 volts out the other side. What makes this remarkable is that the two sides can have up to 5000 volts between them. This chip contains a DC-DC […]

Reverse-engineering the audio amplifier chip in the Nintendo Game Boy Color

Ken has written an article on reverse engineering the audio amplifier chip in the Nintendo Game Boy Color: The Nintendo Game Boy Color is a handheld game console that was released in 1998. It uses an audio amplifier chip to drive the internal speaker or stereo headphones. In this blog post, I reverse-engineer this chip […]

Inside the Am2901: AMD’s 1970s bit-slice processor

Ken posted an article taking a closer look at AMD’s Am2901 chip: You’re probably familiar with modern processors made by Advanced Micro Devices. But AMD’s processors go back to 1975, when AMD introduced the Am2901. This chip was a type of processor called a bit-slice processor: each chip processed just 4 bits, but multiple chips […]

Deconstructing Sega’s System 16 security – part 2

Sega’s FD1089 security module reverse engineering part 2: The FD1089 module variants from Hitachi / SEGA were fabricated in a plastic case, on the back of the module a epoxy layer is visible together with two rows of pins arranged as DIP64. This arrangement mimics a standard 68000 CPU as intended by SEGA. The sample […]

A circuit board from the Saturn V rocket, reverse-engineered and explained

Ken Shirriff writes, “In the Apollo Moon missions, the Saturn V rocket was guided by an advanced onboard computer system built by IBM. This system was built from hybrid modules, similar to integrated circuits but containing individual components. I reverse-engineered a circuit board from this system and determined its function: Inside the computer’s I/O unit, […]

Repairing a vintage 40-kilovolt xenon lamp igniter

Ken Shirriff writes: What do xenon lamps and the invention of radio have in common? The box below is a 1960s German high voltage unit that CuriousMarc obtained as part of an auction. After some research, we determined that it is an Osram1 igniter2, which generates a 40-kilovolt pulse3 to ignite a xenon arc lamp. […]

Inside a Titan missile guidance computer

Ken Shirriff has written an excellent in-depth look at a Titan missile guidance computer: I’ve been studying the guidance computer from a Titan II nuclear missile. This compact computer was used in the 1970s to guide a Titan II nuclear missile towards its target or send a Titan IIIC rocket into the proper orbit. The […]

Inside the digital clock from a Soyuz spacecraft

Ken Shirriff has written an article on reverse engineering a “Onboard space clock” from a Soyuz mission: We recently obtained a clock that flew on a Soyuz space mission.1 The clock, manufactured in 1984, contains over 100 integrated circuits on ten circuit boards. Why is the clock so complicated? In this blog post, I examine […]

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 […]