Column repair in a memory system using a repair cache

A main memory includes a first plurality of input/outputs (I/Os) configured to output data stored in the main memory in response to a read access request. A first portion of the first plurality of IOs provides user read data in response to the read access request and a second portion of the first plurality of IOs provides candidate replacement IOs. Repair circuitry is configured to selectively replace one or more IOs of the first portion of IOs using one or more of the candidate replacement IOs of the second portion of IOs to provide repaired read data in response to the read access request in accordance with repair mapping information corresponding to an access address of the read access request. A static random access memory (SRAM) stores repair mapping information, and a repair cache stores cached repair mapping information from the SRAM for address locations of the main memory.