Hardware manual

Rev. 3.0, 09/98, page 27 of 361
2.4.2 Memory Data Formats
Figure 2.4 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.
7
MSB
MSB
MSB
MSB
MSB
Address n
Address n
Even address
Odd address
Even address
Odd address
Even address
Odd address
654
Upper 8 bits
Lower 8 bits
CCR
CCR*
3210
LSB
LSB
LSB
LSB
LSB
70
Data formatAddress
1-Bit data
Byte data
Word data
Byte data (CCR) on stack
Word data on stack
Data type
Note: * Ignored when returned
Legend
CCR: Condition Code Register
Figure 2.4 Memory Data Formats
When the stack is addressed by register 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.