In a semiconductor memory incorporating therein a circuit for relieving a
defective memory cell, a memory cell array constituted of a number of main
memory cells MC.sub.00 to MC.sub.ij is added with one column of redundant
memory cells MC.sub.0j+1 to MC.sub.ij+1 and one word line of substitution
information storing memory cells MCRA.sub.0 to MCRA.sub.j+1. In only a
first cycle after the power supply is turned on, the substitution
information DR0 to DRj is read out from the substitution information
storing memory cells by use of a writing/reading circuit associated with
the main memory cells, and is transferred to and held in a control
circuit. In a second and succeeding cycles, the control circuit generates
Y selection circuit control signals CS0 to CSj on the basis of the
substitution information held in the control circuit, and a Y selection
circuit is controlled by the control signals CS0 to CSj so as to
selectively connect the columns other than a defective column to an
input/output line. Thus, a chip area overhead attributable to the
installation of the defective memory cell relief circuit is minimized. In
addition, an address comparing circuit for a defective memory cell
substitution is no longer necessary, and an access time overhead
attributable to the address substitution operation does not occur.
