P89V51RD2 Philips Semiconductors, P89V51RD2 Datasheet - Page 17

• Manufacturer Part Number: P89V51RD2
• Description: 8-bit 80C51 5 V low power 64 kB Flash microcontroller with 1 kB RAM
• Manufacturer: Philips Semiconductors

Philips Semiconductors
9397 750 12964
Product data
7.1.4 Dual data pointers
The device has two 16-bit data pointers. The DPTR Select (DPS) bit in AUXR1
determines which of the two data pointers is accessed. When DPS = 0, DPTR0 is
selected; when DPS =
pointers can be accomplished by a single INC instruction on AUXR1 (see
Fig 5. Internal and external data memory structure.
Fig 6. Dual data pointer organization.
2FFH
000H
2FFH
000H
DPS = 0
DPS = 1
EXPANDED RAM
AUXR1 / bit0
ADDRESSING)
DPS
EXPANDED
(INDIRECT
768 Bytes
Rev. 01 — 01 March 2004
RAM
DPTR0
DPTR1
1
, DPTR1 is selected. Quickly switching between the two data
DPH
83H
FFFFH
0300H
FFH
7FH
80H
00H
(INDIRECT & DIRECT
LOWER 128 BYTES
UPPER 128 BYTES
DPL
82H
INTERNAL RAM
INTERNAL RAM
ADDRESSING)
ADDRESSING)
ADDRESSING)
EXTRAM = 0
EXTERNAL
(INDIRECT
(INDIRECT
MEMORY
8-bit microcontrollers with 80C51 core
DPTR1
DATA
DPTR0
external data memory
© Koninklijke Philips Electronics N.V. 2004. All rights reserved.
FFFFH
0000H
FFH
80H
P89V51RD2
REGISTERS (SFRs)
ADDRESSING)
ADDRESSING)
EXTERNAL
FUNCTION
(INDIRECT
EXTRAM = 1
MEMORY
SPECIAL
(DIRECT
DATA
002aaa518
002aaa517
Figure
17 of 75
6).