The relationship between FLASH, RAM and ROM

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The relationship between FLASH, RAM and ROM [Copy link]

       FLASH is mainly used as program storage, which is to replace the previous ROM. The biggest advantage is that it reduces the cost of the chip and can be electrically erased. At present, the life of FALSH in the single-chip microcomputer on the market varies greatly, with the number of erases ranging from 1,000 to 100,000, but the storage time can be guaranteed for 40 years. Pay attention when choosing. Some cheap single-chip microcomputers do not use expensive EEPROM to integrate power-off data storage, but use FALSH. However, it should be noted that its life is at most 100,000 times, and it cannot be erased byte by byte. This requires attention to whether its life meets the requirements in the occasion of use. RAM is a data storage device, which is similar to the memory in the computer. It is mainly used to store process data during program operation. After power failure, the previous data will be lost, so the program needs to be initialized when powered on, otherwise the data after power on is a random number, which may cause the program to crash. ROM is a program storage device. The data will not be lost after power failure, but its data will not change during program operation. The ROM of early microcontrollers has been replaced by the current FLASH memory because of the trouble of erasing and modifying, the high price or the inability to modify data of the cheap OTP type. Because FLASH is easy to erase and write, some microcontrollers now support online internal programming. Through a specific program execution method, the content of FALSH can be modified to achieve online modification of program memory. This does not conflict with the above-mentioned content of the program memory cannot be changed during operation, because when the program is running normally, its content will not change and it only works in a read-only state.