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David Anders (prpplague)
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Recreating Import Documentation - Documentation is King!

_One of the first things I started doing as part of the WITCH-E project was collecting documentation. This article from the August 1951 edition of Electronic Engineering magazine provide a fantastic amount of information about the fundamental design of the WITCH, however the text along with the diagrams were in a terrible state. The scans of the document were very low resolution and the text of course was not searchable. Over a period of a year, the text was painstakingly converted into digital text, and a friend (+Matt Tuomala) tediously recreated the figures and diagrams. After doing some editing and side-by-side comparisons we had a solid recreation of the original document. This document continues to be a cornerstone of the WITCH-E project and in the new digital format can continue to educate into the future. _

http://www.witch-e.org

#witch #witch-e #harwell-witch #harwellwitch #tnmoc #retrocomputing #historicalcomputing #historical-computing

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More Blowback from Autodesk's Eagle License Disaster
Ready to switch to CircuitStudio® Powered by Altium? Special pricing is now available for EAGLE™ users. Switch today for as low as $495 to CircuitStudio.
really stupid move +Autodesk! the high end users are moving to other commercial packages and the lower end users are moving to kicad. way to go +Autodesk! Eagle will be basically worthless this time next year...
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New http://Hackaday.io pages for WITCH-E
i've been hoping for more interaction and interest in the WITCH-E project so i've decided to move project updates and status to http://hackaday.io where i will post most of the ongoing development....


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Keypad Encoder
using basic diode steering, the keypad inputs are encoded to a 5-bit baudot like code(https://en.wikipedia.org/wiki/Baudot_code). the one that is used on the original WITCH is a variation of the standard Baudot code which was modified to make encoding of math operations easier(http://witch-e.org/images/b/be/Witch-tape-encoding.jpg). i could have made this board a lot smaller using some surface mounted device(SMD) diodes, but i had this vintage box of Texas Instruments 1N916A switching diodes (https://www.fairchildsemi.com/datasheets/1N/1N914.pdf) that i thought would look nice to use. the date code on the box seems to indicate the middle of August 1970 as the production date....
http://www.witch-e.org
#witch-e #witch #harwellwitch #tnmoc

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2/20/17
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Manual Entry Keypad Assembled
Slowly moving along on WITCH-E... new PCBs arrived today...
The original WITCH has a manual input panel in order to input commands. this is manual for testing and selecting control of which tape readers to start executing from. For WITCH-E it is an intermediate step between having the tape readers working and being able to fully test the system... next board to be assembled is the keypad encoder which will take the keypad input and cover it to a 5-bit baudot like encoding...
http://www.witch-e.org
#witch-e #witch #harwell-witch #tnmoc

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