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MSM64422/64424

Data Memory

RAM, EEPROM and special function registers (SFRs) are assigned to the Data Memory Address

Space. These Memory are located in a different address space from program memory.

The data length of the Data Memory is 4 bits (1 nibble). The Data Memory uses two banks (256

nibbles/bank): one for the SFR and EEPROM areas using part of the bank 0 and the other for

the RAM area, containing the stack in the bank 7.

BANK7

BANK0

4 bits

4 bits

RAM area

Data/Stack area

128N

128N

Inaccessible

area

EEPROM area

SFR area

HALT

MIEF

Other SFR area

124N

07FH

07EH

07DH

07CH

000H

000H

07FH

0FFH

1FFH

2FFH

3FFH

4FFH

5FFH

6FFH

7FFH

Stack pointer

EEPROM area

128N

128N

128N

(MSM64424)

(MSM64424)

BANK0

0FFH

080H

Data/Stack area

64N

64N

(MSM64422)

EEPROM area

64N

64N

(MSM64422)

Note

: "N" means data length of 4 bits.

Data Memory Address Space

The Data Memory Address Space configuration is shown in the figure alove.

The stack area is a data save area for subroutines and interrupts from the address 7FFH toward

the lower-order addresses (64N max. for MSM64422, 128N max. for MSM64424) by subroutine

call instruction.

For the bank 0, the special function register area from the addresses from 000H to 07FH and 64

nibble EEPROM area from the addresses 080H to 0BFH for MSM64422 or 128 nibble EEPROM

area from the addresses 080H to 0FFH for MSM64424 are assigned.