Memory Data Formats; Figure 2.4 Memory Data Formats - Renesas H8/3847R Series Hardware Manual

Section 2 CPU
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
CCR: Condition code register
Note: * Ignored on return
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.
Rev. 6.00 Aug 04, 2006 page 46 of 680
REJ09B0145-0600
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
MSB CCR*
MSB
0
2 1 0
LSB
LSB
LSB
LSB
LSB