How did punched cards allow the Jacquard loom to follow weaving instructions?

The Jacquard loom utilized punched cards as a programmable medium to automate intricate weaving patterns. The system functioned through a mechanical interface between the cards and the loom’s lifting mechanism.12

Each card corresponded to a single throw of the shuttle. The loom featured a series of horizontal needles connected to "hooks" that controlled individual warp yarns. As a card moved into position on a cylinder, the needles encountered the card's surface:3

• Holes: When a needle aligned with a hole, it passed through, allowing the corresponding hook to remain engaged with the lifting mechanism (the griff). This raised the specific warp thread to form the pattern.3
• Solid areas: Where no hole existed, the needle was pushed back, dislodging the hook from the griff and preventing that specific warp thread from being raised.3

By automatically cycling through a deck of these cards, the loom could execute complex, pre-designed patterns without manual intervention, effectively serving as an early form of information processing and machine programming.24