With the development of smart phones, whether it is looking at the configuration of mobile phones or often in the life and the network are often heard by some people to discuss some words. For example, how much RAM or mobile phone RAM is used. Everyone knows that the larger the ROM or the RAM, the better, but what does the ROM and RAM mean and the difference between the two is not known.
Simply put, a complete computer system consists of software and hardware. Among them, the hardware part is composed of a central processing unit CPU (including an arithmetic unit and a controller), a memory, and an input/output device. At present, motherboards used on personal computers can only support up to 1GB of memory. Even Intel's current highest-end 450NX chipset can only support 4GB.
One of the main functions of a microcontroller is the processing of data information. In the process of processing data, some "containers" are needed to store the data. This is like using pots and pans for cooking. Here, we call these "containers" "memory".
The physical essence of memory is a set (or groups) of integrated circuits with data input/output and data storage functions that act as device buffers or to store the same programs and data. Memory can be divided into read-only memory ROM and random memory RAM according to the function of storing information.
RAMRAM refers to a memory that can be accessed by random and individual access to individual memory cells by instructions. The general access time is basically fixed regardless of the memory cell address. RAM is faster, but its saved information requires power support. Once the power is lost, the data disappears, so it is also called volatile memory. Another interesting name is “volatile memoryâ€. Of course, “volatility†here. What is lost is the data, not the physical chip. In 51 single-chip microcomputers, RAM is mainly used to store data, intermediate results, and running programs, so RAM is also called data memory.
ROMROM English concept is Read Only Memory, read-only memory, in the computer, is a type of memory. This type of memory is often used to store important or confidential data. Ideally, this type of memory is only readable and not allowed to be erased. In 51 single-chip microcomputers, ROM is generally used to store constants, data tables, program codes, etc., so it is also called program memory.
ROM and RAM differenceAs for the main difference between ROM and RAM, I believe everyone has already thought of it. In the mobile phone, RAM refers to the mobile phone memory, which belongs to the internal memory of the mobile phone. It belongs to the random storage and is faster than the ROM. It plays an important role in the performance of the mobile phone. In addition, after the power is turned off, the data is cleared. For example, the mobile phone runs QQ and other. Software, after restarting the phone, the software is not in the login state, which is better understood.
The ROM is external storage. For example, we can often buy the SD card into the mobile phone, which is the mobile phone ROM. The mobile phone ROM is the memory card we usually say, and it can also be simply understood as the mobile phone hard disk. It is used to store mobile phone system files, pictures, movies, etc., and will not lose data with power loss. The larger the ROM, the more data is stored.
The ROM stores the instruction code and some fixed values, and the program cannot be changed after the program is run; the RAM is used for random access of the data during the running of the program, and the data disappears after the power is turned off. .
The ROM is a read only memory. The information in the ROM can only be read after being written once, and cannot be modified or deleted by the operator. Generally used to store fixed programs or data tables.
Cannot be modified or deleted by the operator. Generally used to store fixed programs or data tables.
Of course, the concept of "read-only" "traditional" can sometimes be subverted by devices with new features. The two types of ROM described below can be erased or rewritten using appropriate methods.
EPROM
EPROM differs from a general ROM in that it can erase or rewrite contents with special devices.
2. Flash FLASH
Flash memory, also known as PEROM, is completely non-volatile, can be written online, and can be written in consecutive bytes of page, and the read speed is fast.
RAM is random access memory. This is what we usually call memory, mainly used to store various field input / output data, intermediate calculation results, and exchange information with external memory, or for stacking. Its storage unit can be read or rewritten according to specific needs.
RAM can only be used to temporarily store programs and data. Once the power is turned off or a power outage occurs, the data in the RAM is lost. The data in the ROM will remain after the power is turned off or powered off. This may be the biggest difference between the two.
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