Random Access Memory (RAM), also known as main memory, is an internal memory that directly exchanges data with CPU. You can read and write at any time (except when refreshing), which is very fast. It is usually used as a temporary data storage medium for operating systems or other running programs.
RAM can write (store) or read (take out) information from any designated address at any time when it is working. The biggest difference between it and ROM is the volatility of data, that is, once the power is cut off, the stored data will be lost. RAM is used in computers and digital systems to temporarily store programs, data and intermediate results.
Extended data:
RAM consists of memory matrix, address decoder, read/write controller, input/output, chip selection control, etc.
1, the core part of RAM is a register matrix, which is used to store information, called a memory matrix.
2. Address decoder. The function of the address decoder is to translate the binary number corresponding to the register address into effective row selection signals and column selection signals, so as to select the memory cells.
3. Read/write controller. When accessing RAM, whether to read or write the selected register is controlled by the read and write signals. During the reading operation, the data of the selected unit is transmitted to the CPU (Central Processing Unit) through the data line and the input/output line; When writing, the CPU stores data into the selected cell through input/output lines and data lines.
4. Input/output. RAM exchanges data with CPU of computer through input/output terminal. When reading, it is an input terminal, and when writing, it is dual-purpose. Controlled by a read/write control line. The number of input/output data lines is the same as the number of corresponding register bits in the address, and some RAM chips have separate input/output terminals. Generally, the output of RAM has a open collector or tri-state output structure.
5. Chip selection control. Limited by the integration of RAM. The storage system of a computer usually consists of a lot of ram. When the CPU accesses the memory, it can only access one piece (or several pieces) of RAM at a time, that is, only one address in one piece (or several pieces) of RAM in the memory accepts the CPU's access and exchanges information with it, and the other pieces of RAM are not in contact with the CPU. Chip selection is used to achieve this control.
Usually, a piece of RAM has one or several rows to select. When the row selection of a chip is connected to the active level, the chip is selected, and the register of the address of the chip controlled by the output signal of the address decoder is connected to the CPU. When the chip line is connected to the invalid level, the chip is disconnected from the CPU.
Baidu Encyclopedia-Random Access Memory