UM10147_2
© NXP B.V. 2008. All rights reserved.
User manual
Rev. 02 — 28 April 2008
20 of 134
NXP Semiconductors
UM10147
P89LPC952/954 User manual
1.4 Memory organization
The various P89LPC952/954 memory spaces are as follows:
DATA —
128 bytes of internal data memory space (00h:7Fh) accessed via direct or
indirect addressing, using instruction other than MOVX and MOVC. All or part of the Stack
may be in this area.
IDATA —
Indirect Data. 256 bytes of internal data memory space (00h:FFh) accessed via
indirect addressing using instructions other than MOVX and MOVC. All or part of the
Stack may be in this area. This area includes the DATA area and the 128 bytes
immediately above it.
SFR —
Special Function Registers. Selected CPU registers and peripheral control and
status registers, accessible only via direct addressing.
XDATA —
‘External’ Data or Auxiliary RAM. Duplicates the classic 80C51 64 kB memory
space addressed via the MOVX instruction using the DPTR, R0, or R1. All or part of this
space could be implemented on-chip. The P89LPC952/954 has 256 bytes of on-chip
XDATA memory.
CODE —
64 kB of Code memory space, accessed as part of program execution and via
the MOVC instruction. The P89LPC952/954 has 8 kB/ 16 kB of on-chip Code memory.
Fig 5.
P89LPC952 memory map - P89LPC954 is similar
002aaa948
0000h
03FFh
0400h
07FFh
0800h
0BFFh
0C00h
0FFFh
SECTOR 0
SECTOR 1
SECTOR 2
SECTOR 3
1000h
13FFh
1400h
17FFh
1800h
1BFFh
1C00h
1E00h
1FFFh
SECTOR 4
SECTOR 5
SECTOR 6
FFEFh
FF00h
IAP entry-
points
SECTOR 7
ISP CODE
(512B)*
SPECIAL FUNCTION
REGISTERS
(DIRECTLY ADDRESSABLE)
128 BYTES ON-CHIP
DATA MEMORY (STACK,
DIRECT AND INDIR. ADDR.)
4 REG. BANKS R[7:0]
data memory
(DATA, IDATA)
DATA
128 BYTES ON-CHIP
DATA MEMORY (STACK
AND INDIR. ADDR.)
IDATA
(incl. DATA)
FFEFh
FF1Fh
FF00h
entry points for:
-51 ASM. code
-C code
IDATA routines
1FFFh
1E00h
entry points for:
-UART (auto-baud)
-I2C, SPI, etc.*
Flexible choices:
-as supplied (UART)
-Philips libraries*
-user-defined
ISP serial loader
entry
points
Read-protected
IAP calls only
Table 4.
Data RAM arrangement
Type
Data RAM
Size (bytes)
DATA
Directly and indirectly addressable memory
128
IDATA
Indirectly addressable memory
256
XDATA
Indirectly addressable using MOVX, MOVC, DPTR, R0, R1
256