Instructions on cards

What changes when instructions are stored separately from the mechanism that executes them?

Perforated paper and cards moved weaving choices into replaceable media. The loom remained physical, but the pattern could change without rebuilding the control mechanism.

Separating instructions from mechanism lets one executor produce many outputs by loading different programs.

Reconstruct the mechanism

1. Encode one row of choices as holes and blanks
2. Present the instruction medium to the reader
3. Select hooks and threads according to the pattern
4. Advance to the next instruction and repeat

Encode a small bitmap as cards and run it through a loom simulator. Add repetition, then state what the card system still cannot express.

Evidence and uncertainty

Credit the chain of Bouchon, Falcon, Vaucanson, Jacquard, craftspeople, and operators rather than inventing a lone-genius origin.

• Punched cards control Jacquard loom — Computer History Museum
• Jacquard cards — Science Museum Group