Hippies, clever hardware and Steve Jobs' body odor: Visiting Apple in 1976
A guest posting from William Fine: I saw the "Jobs" movie yesterday and it revived some ancient memories of my dealings with Jobs and Holt in the "old days"! When I returned home, I researched Rod Holt...
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Reverse-engineering and simulating Sinclair's amazing 1974 calculator with...
I've reverse-engineered the Sinclair Scientific calculator. The remarkable thing about this calculator is they took a simple 4-function calculator chip and reprogrammed its 320-instruction ROM to be a...
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Reverse-engineering the 8085's decimal adjust circuitry
In this post I reverse-engineer and describe the simple decimal adjust circuit in the 8085 microprocessor. Binary-coded decimal arithmetic was an important performance feature on early microprocessors....
View Article9 Hacker News comments I'm tired of seeing
As a long-time reader of Hacker News, I keep seeing some comments they don't really contribute to the conversation. Since the discussions are one of the most interesting parts of the site I offer my...
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Reverse-engineering the Z-80: the silicon for two interesting gates explained
I've been reverse-engineering the Z-80 processor, using images from the Visual 6502 team. One interesting thing about the Z-80's silicon is it uses complex gates with multiple inputs and multiple...
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Intel x86 documentation has more pages than the 6502 has transistors
Microprocessors have become immensely more complex thanks to Moore's Law, but one thing that has been lost is the ability to fully understand them. The 6502 microprocessor was simple enough that its...
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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 still used in embedded systems and TIgraphingcalculators. I...
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The Z-80's 16-bit increment/decrement circuit reverse engineered
The 8-bit Z-80 processor was very popular in the late 1970s and early 1980s, powering many personal computers such as the Osborne 1, TRS-80, and Sinclair ZX Spectrum. It has a 16-bit...
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How Hacker News ranking really works: scoring, controversy, and penalties
Update (11/18): article on penalties is penalized Ironically, this article was penalized on Hacker News. Minutes after reaching the front page, a heavy 0.2 penalty was applied to the article, forcing...
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Bitcoins the hard way: Using the raw Bitcoin protocol
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View ArticleBitcoin transaction malleability: looking at the bytes
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The Bitcoin malleability attack graphed hour by hour
I have a new Bitcoin article: Hidden surprises in the Bitcoin blockchain The Bitcoin network was subject to a strange attack this week. Up to 25% of the recorded transactions were modified using a...
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Hidden surprises in the Bitcoin blockchain and how they are stored: Nelson...
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Bitcoin mining the hard way: the algorithms, protocols, and bytes
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The programming error that cost Mt Gox 2609 bitcoins
In October 2011, Mt Gox lost over 2609 bitcoins by accidentally creating transactions that can never be redeemed. (At the time, 2609 bitcoins were worth about $8000, but they would be worth almost $1.5...
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iPad charger teardown: inside Apple's charger and a risky phony
div.ipad-img { position:relative; display:inline-block; } div.ipad-label { position:absolute; top: 5px; left: 5px; color: #444; font-size: 18px; font-family: arial; } This article is now available in...
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Reverse-engineering the TL431: the most common chip you've never heard of
A die photo of the interesting but little-known TL431 power supply IC provides an opportunity to explore how analog circuits are implemented in silicon. While the circuit below may look like a maze,...
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Reverse engineering a counterfeit 7805 voltage regulator
Update: It turns out my 7805 isn't counterfeit. eclectro did an in-depth search (details on reddit) and found an old 7805 datasheet from Thomson Semiconductors that exactly matches my chip. And Thomson...
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Why the Z-80's data pins are scrambled
If you look closely at the datasheet for a Z-80 chip, you'll notice the data pins are in a random-looking order. The address pins (A) are nicely arranged in order counterclockwise from 0 to 15, but the...
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Mining Bitcoin with pencil and paper: 0.67 hashes per day
I decided to see how practical it would be to mine Bitcoin with pencil and paper. It turns out that the SHA-256 algorithm used for mining is pretty simple and can in fact be done by hand. Not...
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