SRAM and SDRAM, norFLASH and nandFLASH difference

1 SRAM and SDRAM difference

1.1 SRAM

　　Memory access function of a stationary, i.e. does not need to refresh circuit that can be stored internally stored data, usually in the buffer between the CPU and main memory (extended memory) with a small-capacity, high speed (stm32f429 is 256K). Advantages: fast, does not have to cope with the memory refresh circuit, the working efficiency can be improved. Disadvantages: low integration and low cost.

1.2 SDRAM

　　Synchronous dynamic random access memory. Synchronization: synchronization clock required; Dynamic: need to constantly refresh the memory array to ensure that data is not lost, random: the address can be randomly assigned. Main memory is typically used (cost, large capacity) advantages: high integration, low power consumption, high cost. Disadvantages: a refresh circuit speed is low.

2 norFLASH and nandFLASH

2.1 norFLASH

　　Read Read NOR Flash and SDRAM most common is the same, each byte can easily access to the inside, the user can run the code is loaded directly inside the NOR FLASH, SRAM can be reduced so that the capacity of the saving cost. But the slow write and erase.

2.2 nandFLASH

　　NAND Flash technology did not take random access memory, read and write usually blocks of 512 bytes, the writing speed is faster than norFLASH. U disk is nandFLASH