at89c51re2-slsem ATMEL Corporation, at89c51re2-slsem Datasheet - Page 39

• Manufacturer Part Number: at89c51re2-slsem
• Description: At89c51re2 8-bit Flash Microcontroller
• Manufacturer: ATMEL Corporation

Mapping of the Memory Space
7663B–8051–03/07
By default, the user space is accessed by MOVC A, @A+DPTR instruction for read
only. Setting FPS bit in FCON register takes precedence on the EXTRAM bit in AUXR
register.
The other memory spaces (user, extra row, hardware security) are made accessible in
the code segment by programming bits FMOD2:0 in FCON register in accordance with
Table 24. A MOVC instruction is then used for reading these spaces.
Thanks to the columns latches access , it is possible to write FM0 array, HSB and extra
row blocks. The column latches space is made accessible by setting the FPS bit in
FCON register. Writing is possible from 0000h to FFFFh, address bits 6 to 0 are used to
select an address within a page while bits 14 to 7 are used to select the programming
address of the page.
Table 24. .FM0 blocks select bits
FMOD2
0
0
0
0
1
1
1
1
FMOD1
0
0
1
1
0
0
1
1
FMOD0
0
1
0
1
0
1
0
1
FM0 array(0000h-FFFFh)
Extra Row(00h-80h)
Erase FM0
Colum latches reset
HSB
FCB
Reserved
Adressable Space
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