Ken Shirriff's Blog
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Inside the Apollo Guidance Computer's core memoryThe Apollo Guidance Computer (AGC) provided guidance, navigation and control onboard the Apollo flights to the Moon. This historic computer was...
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Accounting machines, the IBM 1403, and why printers standardized on 132 columnsHave you ever wondered why 132 characters is such a common width for printers? Many printers produced lines of 132 characters, such as the...
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Hammer time: fixing the printer on a vintage IBM 1401 mainframeThe Computer History Museum has two operational IBM 1401 computers used for demos but one of the printers stopped working a few weeks ago....
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Two bits per transistor: high-density ROM in Intel's 8087 floating point chipThe 8087 chip provided fast floating point arithmetic for the original IBM PC and became part of the x86 architecture used today. One unusual...
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Bad relay: Fixing the card reader for a vintage IBM 1401 mainframeAs soon as we finished repairing a printer failure at the Computer History Museum , Murphy's law struck and the card reader started...
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The printer that wouldn't print: Fixing an IBM 1401 mainframe from the 1960sThe Computer History Museum has two operational IBM 1401 computers used for demos , but a few weeks ago one computers suddenly couldn't print...
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Glowing mercury thyratrons: inside a 1940s Teletype switching power supplyWe recently started restoring a Teletype Model 19, a Navy communication system introduced in the 1940s. 14 This Teletype was powered by a bulky...
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Inside the die of Intel's 8087 coprocessor chip, root of modern floating pointLooking inside the Intel 8087, an early floating point chip, I noticed an interesting feature on the die: the substrate bias generation circuit. In...
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Silicon die analysis: an op amp with interesting "butterfly" transistorsThe TL084 is an op amp chip with an unusual silicon die. Under a microscope, you can see large structures that look kind of like butterflies. These...
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Inside the 76477 Space Invaders sound effect chip: digital logic implemented with I2LThe 76477 Complex Sound Generation chip (1978) provided sound effects for Space Invaders 1 and many other video games . It was also a...
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Bitcoin (BTC), Ripple’s XRP, Ethereum (ETH), Litecoin (LTC) are The Big Deal of 201911 total views, 6 views today BTC, ETH, XRP, LTC – The year 2017 was a defining moment in the lifespan of...
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QuadrigaCX Imbroglio Continues: Cotten Mentioned Bitcoin Key Loss In 2014Since NewsBTC’s last updates on the QuadrigaCX situation, little knowledge has been garnered about the current whereabouts or legitimacy...
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Central Bank Digital Currencies Are a Trojan Horse for BitcoinCentral bank digital currencies (CBDCs) and Bitcoin could scarcely be more different. One is permissioned, the other permissionless; one...
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Top 20 Price Analysis: Ontology (ONT), Litecoin (LTC) Get Bullish Crossover With Signs Of Life2 total views, 2 views today The crypto market is deadening, but some coins are signaling life in the space with green...
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Crypto Tidbits: Meet JP Morgan Coin, SEC Drops Bitcoin ETF ApplicationAfter last week’s price action, the crypto market quieted down. Bitcoin entered a lull, while altcoins followed close behind. Yet, the...
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CME’s Duffy: Crypto Needs to Brown-Nose Governments to SucceedOver the past year, crypto has struggled from a price standpoint. Thus, many investors that are looking to “HODL” have sought the...
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Still Bearish: There Is Still Time For The Bitcoin Bear Market According to Recent Bitcoin ValuationsTL; DR Bitcoins Valuation Charts reveal that we may still be a few months away from hitting the bottom of the market cycle The charts...
