HD6433640 HITACHI [Hitachi Semiconductor], HD6433640 Datasheet - Page 31

• Manufacturer Part Number: HD6433640
• Description: H8/3644 Series Hardware Manual
• Manufacturer: HITACHI [Hitachi Semiconductor]

2.3.2
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. When word data beginning at an odd
address is accessed, the least significant bit is regarded as 0, and the word data beginning at the
preceding address is accessed. The same applies to instruction codes.
When the stack is accessed using R7 as an address register, word access should always be
performed. The CCR is stored as word data with the same value in the upper 8 bits and the lower 8
bits. On return, the lower 8 bits are ignored.
CCR: Condition code register
Note:
*
Byte data (CCR) on stack
Ignored on return
Memory Data Formats
Word data on stack
Data Type
Word data
Byte data
1-bit data
Figure 2.4 Memory Data Formats
Even address
Even address
Even address
Odd address
Odd address
Odd address
Address
Address n
Address n
MSB
MSB
MSB
MSB
MSB
7
7
6
5
Data Format
Upper 8 bits
Lower 8 bits
4
CCR *
CCR
3
2
1
LSB
LSB
LSB
LSB
LSB
0
0
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