PROGRAMMABLE READ ONLY MEMORY WITH BUILT-IN ERROR CORRECTING FUNCTION

摘要

PROBLEM TO BE SOLVED: To reduce the scale of a PROM circuit with a built-in ECC function and to increase the speed. SOLUTION: Write data are stored in a first PROM, and an error correction code generated from written data is stored in a second PROM. When reading data, based on the read data in the first and second PROM, a detection circuit 1 and a decoder circuit 2 specify the error bit position of read data from the first PROM and generate a correct signal. A '1≈signal is supplied to the AND circuit of a correction circuit 3 selected by the correct signal and bit data from the first PROM are changed to '0'.