AT89C51ID2-SLSIM Atmel, AT89C51ID2-SLSIM Datasheet - Page 25

• Manufacturer Part Number: AT89C51ID2-SLSIM
• Description: C51ID2 64KF TWI 32KHZ PLCC44 3-5.5V IND.
• Manufacturer: Atmel

Dual Data Pointer
Register DPTR
Figure 5. Use of Dual Pointer
4289C–8051–11/05
7
AUXR1(A2H)
The additional data pointer can be used to speed up code execution and reduce code
size.
The dual DPTR structure is a way by which the chip will specify the address of an exter-
nal data memory location. There are two 16-bit DPTR registers that address the external
memory, and a single bit called DPS = AUXR1.0 (see Table 23) that allows the program
code to switch between them (Refer to Figure 5).
DPS
0
DPH(83H) DPL(82H)
DPTR1
DPTR0
External Data Memory
AT89C51ID2
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