Programming Notes; Restriction On Address Location - Hitachi H8/500 Series Hardware Manual

3.9 Programming Notes

3.9.1 Restriction on Address Location

The following restriction applies when instructions are located in on-chip RAM.
• Restriction
Instruction execution cannot proceed continuously from an external address to on-chip RAM in
the ZTAT versions. This restriction does not apply to versions with masked ROM.
• Solution
To execute instructions located in on-chip RAM, use a branch instruction (examples: Bcc, JMP,
etc.) to branch to the first instruction located in on-chip RAM. Do not place instruction code in
the last three bytes of external memory (H'FB7D to H'FB7F).
H'FB7A
H'FB7B
H'FB7C
H'FB7D
H'FB7E
H'FB7F
H'FB80
H'FB81
Execution Disabled
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NOP
NOP
NOP
NOP
NOP
NOP
Not
NOP executable
NOP
H'FB7A NOP
H'FB7B BRA
H'FB7C disp
H'FB7D
H'FB7E
H'FB7F
H'FB80 NOP
H'FB81 NOP
Execution Enabled
78
Do not
place
Branch
instruction
code here