STM32F103RCT6 development board, entry-level ARM board! Many buyers for the RBT6 RCT6 not clear, in fact, the I0 port is exactly the same RBT6-FLASH 128K RAM 20KRCT6-FLASH 256K RAM 48K The shop default sends the use of the STM32F103RCT6 high-capacity FLASH, to facilitate the debugging of more complex procedures require a large number of FLASH places!