89C51单片机内部结构深度解析三：单片机RAM地址空间
单片机的作业寄存器：00H~1FH
单片机在作业时需求处理很多的数据，这些数据有些要用来运算，有些要重复调用，有些用来比较查验，这时单片机就需求有这些方位暂时寄存这些数据，以便利后边数据的处理，而单片机供给暂存数据的当地便是作业寄存器。作业寄存器有4组，每组都是8个作业寄存器R0~R7，经过PSW中的RS1、RS0两位来挑选运用哪一组，假如不选，默许是挑选第0组。
RS1RS0组合为00时，选中第0组作业寄存器，R0~R7地址为00H~07H；
RS1RS0组合为01时，选中第1组作业寄存器，R0~R7地址为08H~0FH；
RS1RS0组合为10时，选中第2组作业寄存器，R0~R7地址为10H~17H；
RS1RS0组合为11时，选中第3组作业寄存器，R0~R7地址为18H~1FH。
真实的RAM：20H~7FH
SFR：special function register，特别功用寄存器的总称，是单片计算机中的一组特别的暂时存储区域，用于动态寄存计算机运转进程的一些状况信息、并依此做相应的操控，一共21个。
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地址 |
高位（MSB） |
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7 |
6 |
5 |
4 |
3 |
2 |
1 |
0 |
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0xFF |
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0xFE |
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0xFD |
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0xFC |
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0xFB |
*CCAP1H |
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0xFA |
*CCAP0H |
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0xF9 |
*CH |
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0xF8 |
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0xF7 |
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0xF6 |
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0xF5 |
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0xF4 |
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0xF3 |
*PCA_PWM1 |
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0xF2 |
*PCA_PWM0 |
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0xF1 |
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0xF0 |
B（通用寄存器B，初值：0000 0000） |
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0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
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0xEF |
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0xEE |
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0xED |
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0xEC |
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0xEB |
*CCAP1L |
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0xEA |
*CCAP0L |
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0xE9 |
*CL |
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0xE8 |
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0xE7 |
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0xE6 |
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0xE5 |
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0xE4 |
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0xE3 |
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0xE2 |
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0xE1 |
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0xE0 |
ACC（累加器，初值：0000 0000） |
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0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
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0xDF |
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0xDE |
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0xDD |
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0xDC |
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0xDB |
*CCAPM1 |
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0xDA |
*CCAPM0 |
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0xD9 |
*CMOD |
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0xD8 |
*CCON |
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0xD7 |
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0xD6 |
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0xD5 |
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0xD4 |
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0xD3 |
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0xD2 |
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0xD1 |
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0xD0 |
PSW（程序状况寄存器，初值：0000 0000） |
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CY |
AC |
F0 |
RS1 |
RS0 |
OV |
F1 |
P |
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0xCF |
*SPDAT |
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0xCE |
*SPCTL |
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0xCD |
*SPSTAT |
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0xCC |
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0xCB |
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0xCA |
*P5M0 |
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0xC9 |
*P5M1 |
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0xC8 |
*P5 |
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0xC7 |
*IAP_CONTR |
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0xC6 |
*IAP_TRIG |
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0xC5 |
*IAP_CMD |
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0xC4 |
*IAP_ADDRL |
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0xC3 |
*IAP_ADDRH |
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0xC2 |
*IAP_DATA |
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0xC1 |
*WDT_CONTR |
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0xC0 |
*P4 |
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0xBF |
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0xBE |
*ADC_RESL |
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0xBD |
*ADC_RES |
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0xBC |
*ADC_CONTR |
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0xBB |
*P4SW |
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0xBA |
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0xB9 |
*SADEN |
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0xB8 |
IP（中止优先级寄存器，初值：0000 0000） |
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*PPCA |
*PLVD |
*PADC |
PS |
PT1 |
PX1 |
PT0 |
PX0 |
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0xB7 |
*IPH |
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0xB6 |
*IP2H |
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0xB5 |
*IP2 |
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0xB4 |
*P4M0 |
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0xB3 |
*P4M1 |
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0xB2 |
*P3M0 |
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0xB1 |
*P3M1 |
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0xB0 |
P3（I/O接口第3组，初值：1×11 1111） |
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P3.7 |
P3.6 |
P3.5 |
P3.4 |
P3.3 |
P3.2 |
P3.1 |
P3.0 |
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0xAF |
*IE2 |
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0xAE |
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0xAD |
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0xAC |
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0xAB |
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0xAA |
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0xA9 |
*SADDR |
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0xA8 |
IE（中止操控寄存器，初值：0000 0000） |
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EA |
*ELVD |
*EADC |
ES |
ET1 |
EX1 |
ET0 |
EX0 |
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0xA7 |
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0xA6 |
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0xA5 |
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0xA4 |
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0xA3 |
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0xA2 |
*AUXR1 |
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0xA1 |
*BUS_SPEED |
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0xA0 |
P2（I/O接口第2组，初值：1111 1111） |
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P2.7 |
P2.6 |
P2.5 |
P2.4 |
P2.3 |
P2.2 |
P2.1 |
P2.0 |
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0x9F |
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0x9E |
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*P1ASF |
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0x9D |
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*BRT |
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0x9C |
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*S2BUF |
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0x9B |
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*S2CON |
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0x9A |
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0x99 |
SBUF（UART串口数据寄存器，初值：xxxx xxxx） |
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0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
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0x98 |
SCON（UART串口操控寄存器，初值：0000 0000） |
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SM0 |
SM1 |
SM2 |
REN |
TB8 |
RB8 |
T1 |
R1 |
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0x97 |
*CLK_DIV |
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0x96 |
*P2M0 |
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0x95 |
*P2M1 |
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0x94 |
*P0M0 |
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0x93 |
*P0M1 |
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0x92 |
*P1M0 |
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0x91 |
*P1M1 |
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0x90 |
P1（I/O接口第1组，初值：1111 1111） |
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P1.7 |
P1.6 |
P1.5 |
P1.4 |
P1.3 |
P1.2 |
P1.1 |
P1.0 |
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0x8F |
*WAKE_CLK0 |
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0x8E |
*AUXR |
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0x8D |
TH1（T1守时/计数器16位寄存器高8位，初值：0000 0000） |
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0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
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0x8C |
TH0（T0守时/计数器16位寄存器高8位，初值：0000 0000） |
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0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
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0x8B |
TL1（T1守时/计数器16位寄存器低8位，初值：0000 0000） |
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0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
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0x8A |
TL0（T0守时/计数器16位寄存器低8位，初值：0000 0000） |
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0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
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0x89 |
TMOD（守时/计数器方法操控寄存器，初值：0000 0000） |
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GATE |
C/T |
M1 |
M0 |
GATE |
C/T |
M1 |
M0 |
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0x88 |
TCON（守时/计数器操控寄存器，初值：0000 0000） |
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TF1 |
TR1 |
TF0 |
TR0 |
IE1 |
IT1 |
IE0 |
IT0 |
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0x87 |
PCON（电源操控寄存器，初值：0011 0000） |
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SMOD |
SMOD0 |
*LVDF |
POF |
GF1 |
GF0 |
PD |
IDL |
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0x86 |
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0x85 |
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0x84 |
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0x83 |
DPH（通用16位指针高8位，初值：0000 0000） |
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0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
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0x82 |
DPL（通用16位指针低8位，初值：0000 0000） |
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0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
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0x81 |
SP（仓库指针，初值：0000 0111） |
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0 |
0 |
0 |
0 |
0 |
1 |
1 |
1 |
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0x80 |
P0（I/O接口第0组，初值：xxxx 1111） |
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P0.7 |
P0.6 |
P0.5 |
P0.4 |
P0.3 |
P0.2 |
P0.1 |
P0.0 |
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