P89V51RB2_09 Datasheet, PDF (19/80 Pages) NXP Semiconductors – 8-bit 80C51 5 V low power 16/32/64 kB flash microcontroller with 1 kB RAM

NXP Semiconductors
P89V51RB2/RC2/RD2
8-bit microcontrollers with 80C51 core
2FFH
EXPANDED
RAM
768 B
000H
(INDIRECT
ADDRESSING)
FFH
(INDIRECT
ADDRESSING)
UPPER 128 B
80H INTERNAL RAM
7FH
LOWER 128 B
INTERNAL RAM
(INDIRECT AND
DIRECT
00H
ADDRESSING)
FFH
(DIRECT
ADDRESSING)
SPECIAL
FUNCTION
80H ^{REGISTERS (SFRs)}
FFFFH
(INDIRECT
ADDRESSING)
EXTERNAL
DATA
MEMORY
FFFFH
(INDIRECT
ADDRESSING)
EXTERNAL
DATA
MEMORY
2FFH
000H
EXPANDED RAM
0300H
EXTRAM = 0
0000H
Fig 6. Internal and external data memory structure
EXTRAM = 1
002aaa517
6.2.8 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 = 1, DPTR1 is selected. Quickly switching between the two data
pointers can be accomplished by a single INC instruction on AUXR1 (see Figure 7).
P89V51RB2_RC2_RD2_5
Product data sheet
Rev. 05 — 12 November 2009
© NXP B.V. 2009. All rights reserved.
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