FACTUAL REFERENCE
PUNCHED MEDIA

Punched cards and paper separate information from the mechanism that acts on it.
A hole or absence of a hole can represent a discrete choice. Rows and columns can
organize many such choices into patterns.

Advantages historically included:
- repeatability
- replaceability
- transportability
- visual inspectability
- mechanical sensing

Once the instruction pattern is external, one machine can perform different work
by receiving different media. That is a major conceptual step toward software,
even when the reader itself is entirely mechanical or electromechanical.