A memory for an artificial neural network (ANN) accelerator is provided. The memory includes a first bank, a second bank and a bank selector. Each bank includes at least two word lines and a plurality of write word selectors. Each word line stores a plurality of words, and each word has a plurality of bytes. Each write word selector has an input port and a plurality of output ports, is coupled to a corresponding word in each word line, and is configured to select a byte of the corresponding word of a selected word line based on a byte select signal. The bank selector is coupled to the write word selectors of the first bank and the second bank, and configured to select a combination of write word selectors from at least one of the first bank and the second bank based on a bank select signal.