SDRAM (Synchronous dynamic random access memory) is a methoods to access memory faster. The main principle of SDRAM is that the address and read/write state is latched only once from the MMU. Once burst mode operation is specified (by another line or other lines), then the memory chip maintains its own counter that increments an internal address counter for each chip select assertion.
This method means that even though the first location to read or write takes the same amount of time as (or slightly more than) before, subsequent locations are faster because there is no need to update the address lines and wait for the memory chips to select the correct locations internally.
In order for SDRAM to be useful, a program must encourage the processor and cache controller to burst read blocks of memory locations. Furthermore, SDRAM is useful only if a cache is available. Otherwise, burst reading ahead cannot be helpful.