2. CPU
Rev.3.00 Jul. 19, 2007 page 33 of 532
REJ09B0397-0300
2.3.2
Memory Data Formats
Figure 2.4 indicates the data formats in memory. For access by the H8/300L CPU, word data
stored in memory must always begin at an even address. In word access the least significant bit of
the address is regarded as 0. If an odd address is specified, the access is performed at the preceding
even address. This rule affects the MOV.W instruction, and also applies to instruction fetching.
Data Format
7
6
5
4
3
2
1
0
Address
Data Type
7
0
Address n
MSB
LSB
MSB
LSB
Upper 8 bits
Lower 8 bits
MSB
LSB
CCR
CCR
*
MSB
LSB
MSB
LSB
Address n
Even address
Odd address
Even address
Odd address
Even address
Odd address
1-bit data
Byte data
Word data
Byte data (CCR) on stack
Word data on stack
Legend:
CCR: Condition code register
Note: Ignored on return
*
Figure 2.4 Memory Data Formats
When the stack is accessed using R7 as an address register, word access should always be
performed. For the CCR, the same value is stored in the upper 8 bits and lower 8 bits as word data.
On return, the lower 8 bits are ignored.
Summary of Contents for F-ZTAT H8 Series
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