AT87C5103-ICSIL datasheet(16/64 Pages) ATMEL

16 / 64 page

AT8xC5103

4134C–8051–09/04

Dual-data Pointer

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 device 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 8) that allows

the program code to switch between them (Refer to Figure 7).

Figure 7. Use of Dual-data Pointer

Table 8. AUXR1: Auxiliary Register 1

Reset Value = XXXX X0X0

Note:

1. User software should not write 1s to reserved bits. These bits may be used in future

8051 family products to invoke new features. In that case, the reset value of the new

bit will be 0, and its active value will be 1. The value read from a reserved bit is

indeterminate.

External Data Memory

AUXR1(A2H)

DPS

DPH(83H) DPL(82H)

DPTR0

DPTR1

543

210

---

DPS

Bit

Number

Bit

Mnemonic Description

7-3

Reserved(1)

The value read from this bit is indeterminate. Do not set this bit.

always stuck at 0

Reserved

The value read from this bit is indeterminate. Do not set this bit.

0DPS

Data Pointer Selection

Clear to select DPTR0.

Set to select DPTR1.

AT87C5103-ICSIL Datasheet(PDF) 16 Page - ATMEL Corporation