Hollerith tabulator and centrifugal pump: what they have in common

1. Step 1. Hollerith tabulator — has part — Relay. Relays controlled the sorting box.
2. Step 2. Relay — evolved into — Programmable logic controller. It replaced relay cabinets.
3. Step 3. Programmable logic controller — is part of — Chemical plant. Process control automation.
4. Step 4. Chemical plant — has part — Pipeline. Pipelines between the vessels.
5. Step 5. Pipeline — has part — Centrifugal pump. Pumping stations.

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