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2.3.2
Memory Data Formats
Figure 2.4 indicates the data formats in memory. The H8/300L CPU can access word data stored
in memory (MOV.W instruction), but the word data must always begin at an even address. If word
data starting at an odd address is accessed, the least significant bit of the address is regarded as 0,
and the word data starting at the preceding address is accessed. The same applies to instruction
codes.
Byte data (CCR) on stack
Word data on stack
Note: * Ignored on return
[Legend]
CCR: Condition code register
When the stack is accessed using R7 as an address register, word access should always be
performed. When the CCR is pushed on the stack, two identical copies of the CCR are pushed to
make a complete word. When they are restored, the lower byte is ignored.
Data Type
Address
1-bit data
Address n
Byte data
Address n
Even address
Word data
Odd address
Even address
Odd address
Even address
Odd address
Figure 2.4 Memory Data Formats
Data Format
7
7
6
5
4
3
MSB
MSB
Upper 8 bits
Lower 8 bits
MSB
CCR
CCR *
MSB
MSB
Rev. 6.00, 08/04, page 31 of 628
0
2
1
0
LSB
LSB
LSB
LSB
LSB
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