<hardware> A digital logic circuit that can be in one of two
states which it switches (or "toggles") between under
control of its inputs. It can thus be considered as a one bit
memory. Three types of flip-flop are common: the SR
flip-flop, the JK flip-flop and the D-type flip-flop (or
latch).
Early literature refers to the "Eccles-Jordan circuit" and the
"Eccles-Jordan binary counter", using two vacuum tubes as
the active (amplifying) elements for each bit of information
storage. Later implementations using bipolar transistors
could operate at up to 20 million state transitions per second
as early as 1963.
