A two-port memory having a read port, a write port and a plurality of identical single-port RAM banks. The capacity of one of the single-port RAM banks is used to resolve collisions between simultaneous read and write accesses to the same single-port RAM bank. A read mapping memory stores instance information that maps logical banks and a spare bank to the single-port RAM banks for read accesses. Similarly, a write mapping memory stores write instance information that maps logical banks and a spare bank to the single-port RAM banks for write accesses. If simultaneous read and write accesses are not mapped to the same single-port RAM bank, read and write are performed simultaneously. However, if a collision exists, the write access is re-mapped to a spare bank identified by the write instance information, allowing simultaneous read and write. Both read and write mapping memories are updated to reflect any re-mapping.