Dual Data Pointer
Register (DPTR)
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 17) that allows the program
code to switch between them (see Figure 7).
Figure 7. Use of Dual Pointer
External Data Memory
7
0
DPS
DPTR1
DPTR0
AUXR1(A2H)
DPH(83H) DPL(82H)
20
AT89C51RB2/RC2
4180E–8051–10/06