37
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.
7
6
5
4
3
2
1
0
7
0
MSB
LSB
MSB
LSB
MSB
LSB
Data Type
Data Format
1-bit data
Byte data
Word data
Longword data
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
When ER7 is used as an address register to access the stack, the operand size should be word size
or longword size.
Содержание H8S/2631
Страница 28: ...xviii Appendix G Package Dimensions 1154 ...
Страница 341: ...316 Transfer SAR or DAR DAR or SAR Block area First block Nth block Figure 9 8 Memory Mapping in Block Transfer Mode ...
Страница 918: ...905 ø DREQ0 DREQ1 tDRQS tDRQH Figure 25 19 DMAC DREQ Input Timing ...
Страница 955: ...943 A 2 Instruction Codes Table A 2 shows the instruction codes ...