A memory controller for a multi-bank random access memory (RAM) such as SDRAM includes a transaction slicer for slicing complex client transactions into simple slices, and a command scheduler for re-ordering preparatory memory commands such as activate and precharge in an order that can be different from the order of the corresponding client transactions. The command scheduler may also re-order memory access commands such as read and write. The slicing and out-of-order command scheduling allow a reduction in memory latency. The data transfer to and from clients can be kept in order.