La logique informatique
(selon les travaux de J.D WARNIER)
L.C.S organizing data in a computer system
So let's go,
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But first (at the risk of repeating myself)
What is a computer system, how does it work?

This is the schema of a logically perfect system, the database is powered and updated from external movements only. The outputs of the system always come from the primary database.
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Even if it is beautiful, in practice it will be necessary to keep in the database, so - called "secondary" data calculated from primary data, in order to limit the volume of data to be kept in the system and of course, Improve the processing times.
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To smile a little: 50 years ago it was stored on perforated cards (well almost !) Then in 50 years to intergalactic air one will perhaps no longer need to keep secondary data !!
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Here is the schematic of the system as it exists in practice.