Detailed analysis of MCS-51 single-chip internal data storage RAM

The 8051 single-chip internal RAM has a total of 256 units, usually divided into two parts according to their functions: low 128 units (unit address 00h ~ 7FH) and high 128 units (unit addresses 80h ~ ffh). As shown in the figure, it is a configuration diagram of a low 128 unit. Register area 8051 There are 4 sets of registers, 8 registers (each 8) each group, and each group is registered in R0 ~ R7. Registers are often used to store intermediate results of the operand. Since their functions and use are not pre-stated, they are called universal registers, sometimes called work registers. 4 sets of general registers occupy the 00H ~ 1FH unit address of the internal RAM. At any time, the CPU can only use a set of registers, and refer to the group of registers being used as the current register group. Which group is made, the status combination of RS1 and RS0 bits in the program status word register PSW is determined. The universal register provides the CPU to facilitate the convenience of storage data, which is conducive to improving the computing speed of the microcontroller. In addition, using universal registers can improve the flexibility of programming, and therefore, these registers should be taken out in the application programming of the microcontroller to simplify the programming and improve program running speed. Bit address area The 20H ~ 2FH unit of the internal RAM can be used as a general RAM unit, and the byte operation can be performed, and each bit in the unit can sense each bit, thus referinging the area as a bit addressing area. A total of 16 RAM units are set in the bit addressing area, 128 bits, and addresses 00h ~ 7FH. The MCS-51 has a Boolean processor function, which can constitute the storage space of the Boolean processor. This bit addressing ability is an important feature of MCS-51. User RAM area In the internal RAM lower 128 unit, the general register accounts for 32 units, and the bit addressing area accounts for 16 units, and the remaining 80 units are left, which is a general RAM zone used by the user, and its unit address is 30H ~ 7FH. There is no provision or restrictions on the use of the user RAM area, but the stack is often opened in this area in general applications. Internal data storage high 128 unit The high 128 unit of the internal RAM is used by a dedicated register, and its unit address is 80h ~ FFH. Because these registers have been specified, the Special Function Register can also be referred to as a special function register. Read the full article, original text title: MCS-51 single-chip internal data storage RAM structure detailed Article Source: [Micro Signal: wujianying_danpianji, WeChat public number: MCU "Welcome to add attention! Please indicate the source of the article.

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