Ken Shirriff's Blog
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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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FizzBuzz the hard way: Generating VGA video output with an FPGApre {border:none;background-color:#eee;display:inline-block;min-width:30em;padding:4px;font-size:80%;} code {background-color:#eee;} In...
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A 1970s disk drive that wouldn't seek: getting our Xerox Alto running againOur vintage Xerox Alto has been running reliably for months, but a couple weeks ago the disk drive malfunctioned and the heads stopped moving....
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Bitcoin (BTC) Falls To $3,400, Crypto Shorts Ramp Up — Sell-Off Inbound?Bitcoin Fails To Breakout, BTC Stumbles To $3,400 — Altcoins Follow Suit After days of unrest in the industry, and the perpetuation of a...
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Bitcoin Climbs to $3,500, Analyst Claims There is Nothing Unique About the Crypto BubbleBitcoin was able to bounce after yesterday’s downturn, leading the entire cryptocurrency market to trade up. The latest move up may validate the...
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Ripple Price Analysis: Break Above 100 SMA Could Push XRP HigherKey Highlights Ripple price declined recently and traded towards the $0.2910 level against the US dollar. This week’s followed major...
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What is Litecoin?In the world of cryptocurrency, numerous projects are competing with one another. Some are worth paying more attention to than others. It is not...
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Bitcoin Core Developer Aims to Improve Transaction RelayDr. Pieter Wuille , the co-founder of Blockstream, a firm which majorly focuses on building software solutions for the Bitcoin Network, has...
