SDRAM means synchronous dynamic random access memory which is a type of solid state computer memory. SDRAM has a synchronous interface, meaning that it waits for a clock signal before responding to its control inputs. It is synchronized with the computer's system bus, and thus with the processor. The clock is used to drive an internal finite state machine that pipelines incoming instructions. This allows the chip to have a more complex pattern of operation than DRAM which does not have synchronizing control circuits. In a pipelined read, the requested data appears after a fixed number of clock pulses after the read instruction, cycles during which additional instructions can be sent. This delay is called the latency and is an important parameter to consider when purchasing SDRAM for a computer.