The program register inside the microcontroller is generally 1K~64K bytes, usually a read-only memory, because most of the microcontroller application systems are dedicated systems. Once the development is successful, the software is also Qualitatively, the program is solidified in the read-only memory, and the read-only memory is used as the program memory. The program will not be lost after power failure, thereby improving the reliability of the system; in addition, the read-only memory has high integration and low cost. According to the different types of internal program memory of the MCU, it can be divided into the following products:
(1) ROM-type MCU: internally has a read-only program memory changed by a factory mask ROM. This kind of single-chip microcomputer is custom-made and generally has the lowest price. The user gives the debugged program code to the manufacturer. The manufacturer solidifies the program into the ROM when making the single-chip microcomputer, and the user cannot modify the code in the ROM. This kind of single-chip microcomputer has the lowest price, but the production cycle is longer. Suitable for mass production.
(2) EPROM type single-chip microcomputer: EPROM type program memory is installed inside. For EPROM type single-chip microcomputer with window, the program in EPROM can be erased by ultraviolet eraser, and the new program code can be changed by programming tool It can be written into EPROM and can be erased and written repeatedly. It is convenient to use, but it is expensive and suitable for developing prototypes. For EPROM type MCU without window, it can only be written once, which is called OTP type MCU. The price of OTP single-chip microcomputer is relatively low, which is suitable for prototype development and mass production.
(3) FLASH Memory type single-chip microcomputer: internally contains FLASH Memory type program memory, users can use a programmer to quickly erase and write byte by byte to FLASH Memory. The price of this type of single-chip microcomputer is also low, Easy to use, it is currently the most popular single-chip microcomputer.