How did early medieval organs produce different notes before modern-style keys developed?

Before the development of modern-style keys, early medieval organs primarily utilized sliders that were pulled out to sound different notes. Some early instruments may have also employed key-shaped levers that turned, similar to the mechanism used for a lock.12

These methods were considered clumsy, as they lacked the ease of the parallel, pivoted levers found on modern keyboards. In some instances, particularly with smaller portable instruments, push buttons were used to control the pipes instead of keys. It was not until the 14th century that a keyboard resembling the modern type began to emerge, though the standardization of key sizes and arrangements continued to evolve through the 15th century and beyond.123