
11
4431E–8051–04/06
AT/TS8xC54/8X2
7.
Dual Data Pointer Register Ddptr
The additional data pointer can be used to speed up code execution and reduce code size in a
number of ways.
The dual DPTR structure is a way by which the chip will specify the address of an external data
memory location. There are two 16-bit DPTR registers that address the external memory, and a
single bit called
DPS = AUXR1/bit0
(See Table 7-1.) that allows the program code to switch between them
Figure 7-1.
Use of Dual Pointer
External Data Memory
AUXR1(A2H)
DPS
DPH(83H) DPL(82H)
0
7
DPTR0
DPTR1