SH7604 Datasheet, PDF (143/633 Pages) Hitachi Semiconductor – Hardware Manual

6.3.8 SH7000 Series Compatible Mode
1. In SH7000 Series compatible mode:
In SH7000 Series compatible mode, functions are as follows:
• The registers shown in the table 6.2 are valid; all others are not.
• External bus breaks are not possible in SH7000 Series compatible mode. The instruction fetch
cycle occurs prior to instruction execution. The flags are not set when break conditions match.
2. Differences between SH7000 Series compatible mode and SH7604 mode:
When set for the CPU instruction fetch cycle in the SH7000 Series compatible mode, the break
occurs before the instruction that matches the conditions. The break conditions differ as shown
below from setting for before-execution in SH7604 mode. For data access cycles, the address
is always compared to 32 bits in the SH7000 Series compatible mode, but in SH7604 mode is
compared as shown in table 6.3. This produces the differences in break conditions shown in
table 6.4.
Table 6.4 Differences in Break Conditions
Match Determination
Conditions match when set for instruction
fetch cycle/before-execution
Conditions match in longword access when
set for addresses other than longword
boundaries (4n address)
Conditions match in word access when set
for addresses other than word boundaries
(2n addresses)
SH7000 Series
Compatible Mode
SH7604 Mode
Breaks if instruction is
overrun-fetched and
not executed (as during
branching)
Does not break if
instruction is overrun
fetched and not executed
(as during branching)
Does not break
Breaks
Does not break
Breaks
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