Actual size of the core plane below is 4.25 inches.  A single bit was
stored in a teeny-tiny ferrite 'doughnut' which was magnetized as being
on or off.  Three wires went through the hole in the doughnut which 
were used to magnetize or demagnetize the bit and to sense its polarity.


The threading of the wires through the doughnuts was done by hand by 
'girls' using stereoscopic microscopes. Presumably, boys were too clumsy.



Eight of these planes would form a stack. Bytes (although the word had
not been invented when core was used) were represented by the bits
on each level at the same x-y coordinates.