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contex_b [2020/08/23 16:54]
clodoveu
contex_b [2020/09/07 15:52] (current)
clodoveu
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 Subtracting in the Class 5 is, as in the Comptometer,​ also troublesome. The operator is required to enter a tens-complement number, using preceding 9s and typing the number to be subtracted by looking at the small numbers on the keycaps. The preceding 9s are actually zeroes if you look at the small numbers in the keycaps. Oh, and the subtrahend must be reduced by one so the tens-complement works correctly. Whew. More on Burroughs Class 5 operation [[http://​public.beuth-hochschule.de/​hamann/​burroughs/​burro5/​index.html|here]]. Subtracting in the Class 5 is, as in the Comptometer,​ also troublesome. The operator is required to enter a tens-complement number, using preceding 9s and typing the number to be subtracted by looking at the small numbers on the keycaps. The preceding 9s are actually zeroes if you look at the small numbers in the keycaps. Oh, and the subtrahend must be reduced by one so the tens-complement works correctly. Whew. More on Burroughs Class 5 operation [[http://​public.beuth-hochschule.de/​hamann/​burroughs/​burro5/​index.html|here]].
  
-There was practically nothing to do in this machine. Its three rubber feet were deteriorated,​ but I was able to replace them with round hydraulic seals, after making a countersinked hole in each one. After a general cleaning, I now only mean to restore the front Contex logo, which is all but invisible, as in the case of many units whose photos can be found online. The case has the makings ​of a lost handle, which I also plan to replace.+There was practically nothing to do in this machine. Its three rubber feet were deteriorated,​ but I was able to replace them with round hydraulic seals, after making a countersinked hole in each one. After a general cleaning, I now only mean to restore the front Contex logo, which is all but invisible, as in the case of many units whose photos can be found online. The case has the markings ​of a lost handle, which I also plan to replace.
  
 **Have a mechanical calculator stored somewhere, and want to get rid of it? Send it to me!** **Have a mechanical calculator stored somewhere, and want to get rid of it? Send it to me!**
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 As purchased As purchased
  
-{{ http://​www.dcc.ufmg.br/​~clodoveu/​files/​Images/​Burroughs/Burroughs_1.jpg?500 | As purchased}}+{{ http://​www.dcc.ufmg.br/​~clodoveu/​files/​Images/​Contex-model-B/20200823 as purchased.png?500 | As purchased}}
  
 +After cleaning
  
 +{{ http://​www.dcc.ufmg.br/​~clodoveu/​files/​Images/​Contex-model-B/​contex-1.jpg?​500 | Contex model B}}
  
-**More about this machine**+Serial number
  
-[[http://www.johnwolff.id.au/calculators/Burroughs/Burroughs.htm John Wolff shows a wider Class 5with 13 columns instead of 9, including ​column for Sterling currency units]]+{{ http://www.dcc.ufmg.br/~clodoveu/files/Images/​Contex-model-B/​contex-2.jpg?​500 ​Contex model B}} 
 + 
 +Inside view 
 + 
 +{{ http://​www.dcc.ufmg.br/​~clodoveu/​files/​Images/​Contex-model-B/​contex-3.png?​500 | Contex model B}} 
 + 
 +Bottom view -- notice the five blades for the keys in each columnarranged as fan 
 + 
 +{{ http://​www.dcc.ufmg.br/​~clodoveu/​files/​Images/​Contex-model-B/​contex-4.png?​500 | Contex model B}} 
 + 
 +**More about this machine**
  
-[[https://www.youtube.com/watch?​v=MpCXcOcAsHk ​Video: a demonstration of the Class 5 in action]]+[[http://www.johnwolff.id.au/calculators/​Contex/​Contex.htm ​John Wolff'​s page on Contex calculators]]
  
-[[http://public.beuth-hochschule.de/hamann/​burroughs/​burro5/​index.html ​An operations description,​ including an explanation on subtraction modes and their special cases]]+[[https://youtu.be/GD8kXroD4gg ​Video: a demonstration of the Contex model B]]
  
-[[http://collection.sciencemuseum.org.uk/objects/co59681/​burroughs-class-5-hand-operated-mechanical-adding-calculating-machine-full-keyboard-adding ​A beautifully preserved unit at the UK'​s ​Science Museum]]+[[https://www.jaapsch.net/mechcalc/contex.htm|Jaap'​s ​mechanical calculators page on the Contex machines]]
  
-[[https://arildamland.artstation.com/projects/k4lBOl | A time-lapse video of an artist recreating the shape of a Class 5 using only a photo and a 3D design software package]]+[[http://public.beuth-hochschule.de/hamann/contex/co-b/​index.html | An operations description,​ including ​an explanation on subtraction]]
  
-[[https://​archive.org/​details/​burr_instr/​page/​n9 | Instructions for Operating the Burroughs Calculator. 36 page booklet]] 
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contex_b.1598212493.txt.gz · Last modified: 2020/08/23 16:54 by clodoveu
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