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September 1, 2021 Archives

Wednesday, September 1, 2021

CONTINUITY: HP 9825 Repair Part 11—Debugging the Keyboard, Display, and Printer Board

The repairs of earlier episodes got the Hewlett-Packard 9825 laboratory computer working, but only with a keyboard, display, and printer module borrowed from a working 9825. Now the focus moves on to repairing the module from the unit fried when its power supply blew up. This is a worrisome task, since this module's circuit board includes a custom Hewlett-Packard application-specific integrated circuit (ASIC) which, all these years later, might as well be made of gold-pressed unobtainium.

Posted at 15:15 Permalink

THE HAPPENING WORLD: Finally—Computer Engineering for Babies

Posted at 14:42 Permalink

TRACKING WITH CLOSEUPS: Using Galactic Supernovæ as SETI Signal Beacons

The research paper is “Search for Galactic Civilizations Using Historical Supernovae”.


We study an interstellar signaling scheme which was originally proposed by Seto (2019) and efficiently links intentional transmitters to ETI searchers through a conspicuous astronomical burst, without prior communication. Based on the geometrical and game theoretic viewpoints, the scheme can be refined so that intentional signals can be sent and received after observing a reference burst, in contrast to the original proposal (before observing a burst). Given this inverted temporal structure, Galactic supernovae recorded in the past 2000 years can be regarded as interesting guideposts for an ETI search. While the best use period of SN 393 has presumably passed ∼100 years ago, some of the historical supernovae might allow us to compactify the ETI survey regions down to less than one percent of 4π, around two rings in the sky.

Posted at 13:52 Permalink

CONTEXT: Giant Viruses and Their Predators

Posted at 13:09 Permalink

CONTINUITY: World Energy Production from 1860 to 2019

Posted at 12:53 Permalink