Card sorter
More info
- Creator
- Herman Hollerith
- Released
- 1901 (IBM Type 80: 1925)
- Type
- Punched-card machine
- Owner
- IBM
The machine that could only sort on one column at a time — and therefore handed the world radix sort, fifty years before anyone called it an algorithm.
A sorter runs cards past a single reading brush and drops each one into one of thirteen pockets: digits 0–9, the two zone punches, and a reject pocket for blanks. It can therefore only order a deck by one character. Sorting a five-digit account number means five passes of the whole deck, and you must start with the least significant digit — otherwise each pass destroys the ordering the previous one established.
That is radix sort exactly, discovered by mechanism rather than by mathematics. Hollerith patented the principle in 1887 for the census; IBM's Type 80 of 1925 managed 250 cards a minute, the Type 84 of the 1950s hit 2,000. An operator who dropped a deck on the floor started again from column one, which is the entire explanation for why card boxes had lids and why people ruled a diagonal stripe in marker across the top edge of a finished deck.