The machine that I had that I used most with core memory was a Seeburg
Jukebox. They used 1 core memory bit for each side of each record. If it
was a "1", that record had been selected for playing. The mechanism scanned
from side to side, stopping at each record with the bit
set for either side.
Records were not played in the order that they were selected or
paid for,
but in the physical left-to-right or right-to-left order.