Memory Data Formats - Hitachi H8S/2646 Hardware Manual

2.5.2

Memory Data Formats

Figure 2-11 shows the data formats in memory. The CPU can access word data and longword data
in memory, but word or longword data must begin at an even address. If an attempt is made to
access word or longword data at an odd address, no address error occurs but the least significant
bit of the address is regarded as 0, so the access starts at the preceding address. This also applies to
instruction fetches.
Data Type
1-bit data
Byte data
Word data
Longword data
When ER7 is used as an address register to access the stack, the operand size should be word size
or longword size.
Address
Address L
Address L
Address 2M
Address 2M + 1
Address 2N
Address 2N + 1
Address 2N + 2
Address 2N + 3
Figure 2-11 Memory Data Formats
Data Format
7
7 6 5 4 3
MSB
MSB
MSB
0
2 1 0
LSB
LSB
LSB
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