Differences
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burroughs_class_5 [2019/05/17 21:12] clodoveu |
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| * [[calc|Back to Mechanical Calculators]] | * [[calc|Back to Mechanical Calculators]] | ||
| - | This machine was manufactured by Burroughs in the United States, at a factory in Detroit, Michigan, in 1926 or 1927 (see [[http://www.burroughsinfo.com/when-was-my-machine-made.html|here]]). I bought it at an online auction site, in May 2019, from just two posted images. I took the chance of buying without being able to see much of the machine's condition, but this one is older, rarer in Brazil, and has a simpler mechanism, based on the Comptometer. Online sources say that Burroughs was sued for nearly copying the Comptometer's working mechanism in other machines, and then came out with the Class 5 with a few innovations, including a more compact design, aiming at desktop use. Earlier bulky Burroughs adding machines were mounted on pedestals and placed at the center of offices, to be shared among many operators. | + | This machine was manufactured by Burroughs in the United States, in Detroit, Michigan, in 1926 (see [[http://www.burroughsinfo.com/when-was-my-machine-made.html|here]]). I bought it at an online auction site, in May 2019, from just two posted images. I took the chance of buying it without being able to see much of the machine's condition, but this one is older, rarer in Brazil, and has a simpler mechanism, based on the Comptometer. |
| - | My unit has seven missing keys, and one white "3" key too many. This was probably a replacement taken from another machine. It was locked and unresponsive, the painted aluminum (?) case sprinkled with paint drops, and all rubber feet crumbling. The decimal point indicators are also missing. Two of the display's numbered wheels are cracked, one badly and slipping from its position. Those must be glued in position to work. | + | Online sources say that Burroughs was sued for nearly copying the Comptometer's working mechanism in other machines, and then came out with the Class 5 with a few innovations, including a more compact design, aiming at desktop use. Earlier bulky Burroughs adding machines were mounted on pedestals and placed at the center of offices, to be shared among many operators. |
| - | Online photos of museum units and other well-preserved Class 5s show, right to left, two columns of white keys, three blacks, three whites and one black. This points to adding money figures, up to 9,999,999.99. My unit has three black columns, three whites, and three blacks. This is probably due to the Brazilian currency prior to 1942, called "réis" (plural of "real"). A single real back then was basically worthless, so money units were called "mil-réis", for thousand reais, and denoted like 1.000$000. Three groups of three columns then make more sense than having two columns for cents, which we did not have back then. The smallest denomination was a 20 réis coin, dubbed the "vintém". The 100 réis coin was called a "tostão", and the highest denomination was worth 1.000$000, or a thousand mil-réis. A million réis was called a "conto de réis". | + | My unit has seven missing keys, and one white "3" key too many. This was probably a replacement taken from another machine. It was locked and unresponsive, the painted aluminum alloy (?) case sprinkled with white paint specks, and all rubber feet crumbling away. The decimal point indicators are also missing. Two of the display's numbered wheels are cracked, one badly and slipping from its position. Those must be glued back in position to work. |
| - | As essentially a Comptometer, this machine does not actually add fully input numbers to an accumulator. As keys are pressed in each column, the mechanism advances the corresponding digit by the required number of positions, and then carry goes to the digit at the left. The operator never actually sees the number being added anywhere: not in the display, nor as a set pf down-pressed keys. The effect of each typed-in digit is immediate, so recognizing and correcting mistakes must have been painful. On the other hand, digits can be input simultaneously, by pressing keys in different columns at the same time -- weird. Also, the effect of pressing, say, 2 and then 5 in a column is the same as pressing a 7 in the same column, but 2 + 5 require less arm and wrist movement. As a result, keys from the bottom rows show much more wear than keys in the top rows. Later machines based on the same principle have only 5 rows of keys, requiring double keypresses to input larger digits. | + | Online photos of museum units and other well-preserved Class 5s show, right to left, two columns of white keys, three blacks, three whites and one black. This points to adding money figures, up to 9,999,999.99. My unit has, right to left, three black columns, three whites, and three blacks. This is probably due to the Brazilian currency prior to 1942, called "réis" (plural of "real"). A single real back then was basically worthless, so money units were called "mil-réis", for thousand reais, and denoted like 1.000$000. Three groups of three columns then make more sense than having two columns for cents, which we did not have back then. The smallest denomination was a 20 réis coin, dubbed the "vintém". The 100 réis coin was called a "tostão", and the highest denomination was worth 1.000$000, or a thousand mil-réis. A million réis was called a "conto de réis". |
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| + | As essentially a Comptometer, this machine does not actually add fully input numbers to an accumulator on command. The lever to the right is only used for clearing. As keys are pressed and released in each column, the mechanism immediately advances the corresponding digit by the required number of positions, and then carry flows to the digit to the left. The operator never actually sees the number being added anywhere: not in the display, nor as a set of down-pressed keys. The effect of each typed-in digit is immediate, so recognizing and correcting mistakes must have been painful. On the other hand, digits can be input simultaneously, by pressing keys in different columns at the same time -- weird. Also, the effect of pressing, say, 2 and then 5 in a column is the same as pressing a 7 in the same column, but 2 + 5 require less arm and wrist movement. As a result, keys from the bottom rows show much more wear than keys in the top rows. Later machines based on the same principle have only 5 rows of keys, requiring double keypresses to input larger digits. | ||
| It is interesting to notice that adding columns of numbers can be done column-wise, giving the same result. Say you need to add 123 + 456 + 789. You can type in 3 - 6 - 9 on the rightmost column, then 2 - 5 - 8 on the second, and 1 - 4 - 7 on the third, much like adding manually. | It is interesting to notice that adding columns of numbers can be done column-wise, giving the same result. Say you need to add 123 + 456 + 789. You can type in 3 - 6 - 9 on the rightmost column, then 2 - 5 - 8 on the second, and 1 - 4 - 7 on the third, much like adding manually. | ||
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| [[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]] | [[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]] | ||
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| + | [[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]] | ||
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| + | [[https://archive.org/details/burr_instr/page/n9 | Instructions for Operating the Burroughs Calculator. 36 page booklet]] | ||
