A method and an apparatus for driving passive matrix liquid crystal,
comprising the steps of: simultaneously selecting Y row electrodes, where
Y is an odd number of 7 and above; calculating an exclusive OR between a
Y-bit row selection vector representing a selection pattern of the Y row
electrodes and Y-bit ON/OFF display data representing a display pattern
of column electrodes, for each corresponding bit; adding the exclusive
ORs for each bit; when X=(Y+1)/2, and a 1/(X-1) voltage of the maximum
voltage of the column electrodes is Vc, selecting a voltage level of the
column electrodes from X voltage levels satisfying:
[2.times.i-(X-1)].times.Vc (i=an integer of 0 to (X-1)) in accordance
with the result of the addition for driving. These method and apparatus
prevent the frame response phenomenon of high-speed liquid crystal while
realizing high-contrast display, low-voltage driving, low power
consumption, and reduction in chip size.