Memory device with failed main bank repair using redundant bank

A system, comprising:

• a memory device configured to store data, the memory device comprising:
• an array of memory cells comprising a first-level memory unit, the first-level memory unit comprising a plurality of second-level memory units, each second-level memory unit comprising N main banks and a redundant bank, where N is a positive integer;
• an input/output (I/O) circuit coupled to a first-level data bus, and configured to direct N pieces of data to or from N working banks in a corresponding second-level memory unit through the first-level data bus and one or more branch data buses, respectively;
• and
• I/O control logic coupled to the I/O circuit and configured to:
• determine the N working banks from the N main banks and the redundant bank in the corresponding second-level memory unit based on bank fail information indicative of a failed main bank of the N main banks;
• and
• control the I/O circuit to direct the N pieces of data to or from the N working banks, respectively;
• and
• a memory controller coupled to the memory device and configured to control the memory device.