# Sram in the ARM cortex m3

I load a project into the chip STM32f103ZC whose internal sram is 48kBytes , there are also 2MBytes external sram on the board. But when I download and debug the project,the map file tells that 52KBytes read write memory has been used. Does it mean the ram? I think it doesn't exist error maybe because the linker command file makes 64KBytes for the ram just like the datasheet as below, but where is the extra data? Is it automatically stored in the external sram? I use the IAR under the Windows in C language.

• The map file also tells you the address of the memory. – Turbo J Apr 21 '15 at 14:35

• Since your external SRAM is 2MB, it will be from 0x60000000 to 0x601fffff, so that's the range you'd define in the linker file. Make sure that the memory controller is configured properly in the initialization code though; on a Cortex-M3 like STM32 it would usually be through SystemInit(). Again, if you're using a demo project for your board it may already be done for you. – Tony K Apr 22 '15 at 19:30