Unterschiede
Hier werden die Unterschiede zwischen zwei Versionen gezeigt.
| Beide Seiten der vorigen Revision Vorhergehende Überarbeitung | |||
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analyticalengine:zeroingtemporaries [2015-04-22 18:11] rainer typo |
analyticalengine:zeroingtemporaries [2015-04-22 20:19] (aktuell) rainer Zero before store asserted |
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| That's why I think a zero is missing in line 24 column V<sub>13</sub>. | That's why I think a zero is missing in line 24 column V<sub>13</sub>. | ||
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| + | From the mechanical plans, it might be required -- but not mentioned in the papers -- that to transfer a value from the mill via the outgress shaft to the store, that store must be zero, otherwise a digit-wise add (without carry) would be done. | ||
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| + | The Bernoulli number example fits perfectly into this scheme. | ||
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| + | In case that an input operand is replaced by the result, it is no problem to use the -- anyhow quicker -- zeroing load. | ||
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| + | Checking the table shows that all (working-) variables are zeroed before replaced with another value: | ||
| + | * In line 9, V<sub>11</sub> is set, but was cleared in line 6 | ||
| + | * in line 15, V<sub>8</sub> is set, was initially zero, and is zeroed in the next line, so if looped, will be zero again | ||
| + | * in line 19, the same is true for V<sub>9</sub> | ||
| + | * same in line 20 | ||
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| + | Thus, it is clear that in line 24, the table should have a zero for V<sub>13</sub>. | ||
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| + | So it is probably not a mere extra, but necessary for the correct functioning. | ||
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| + | ===== Note ===== | ||
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| Zeroing out intermediate values still seems to be current practice when Alan Turing wrote his //On Computational Numbers…//; on page 232: | Zeroing out intermediate values still seems to be current practice when Alan Turing wrote his //On Computational Numbers…//; on page 232: | ||
