3.4.2 Memory Data Formats
Figure 3-4 indicates the data formats in memory.
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, no address error
occurs but the access is performed at the preceding even address. This rule affects MOV.W
instructions and branching instructions, and implies that only even addresses should be stored in the
vector table.
Figure 3-4. Memory Data Formats
When the stack is addressed using R7, it must always be accessed a word at a time. When the CCR
is pushed on the stack, two identical copies of the CCR are pushed to make a complete word.
When they are returned, the lower byte is ignored.
7
0
7 6 5 4 3 2 1 0
1-Bit data
Byte data
Word data
Byte data (CCR) on stack
Word data on stack
Data type
Data format
Address
Address n
Address n
Even address
Odd address
Even address
Odd address
Even address
Odd address
M
S
B
L
S
B
M
S
B
L
S
B
Upper 8 bits
Lower 8 bits
M
S
B
M
S
B
L
S
B
L
S
B
CCR
CCR
*
M
S
B
L
S
B
CCR: Condition Code Register
Note:
*
Ignored when returned
35
Summary of Contents for H8/326 Series
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