Operation Of The Address Match Detection Function - Fujitsu F2MC-16LX Hardware Manual

21.3 Operation of the Address Match Detection Function

When an address matches the value set in the address detection register, the
instruction code to be read by the CPU is replaced with the INT9 instruction code
(01 ). Consequently, the CPU executes the INT9 instruction when it executes specified
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instruction. Program patching is enabled by processing the INT #9 interrupt routine.
■ Operation of the Address Match Detection Function
There are two registers for address detection, each with an interrupt permission bit. When an
address matches the value set in the address detection register and its interrupt permission bit
is set to "1", the instruction code interrupted by the CPU is forcibly replaced with the INT9
instruction code.
■ Note About The Operation of the Address Match Detection Function
The address match detection function is effective only for internal ROM. If an address of
external memory area is set, the INT9 instruction will not be issued.
If an address other than the address of the first byte of the instruction is set to the address
detection registers, this function will not work normally.
changed to 01
Confirm that the interrupt permission bit is "0" before altering the settings of the address
detection registers. If the interrupt permission bit is "1", unwanted address detection may occur
during the writing, which may result in abnormal operation.
, a wrong instruction is executed or wrong address is accessed.
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21.3 Operation of the Address Match Detection Function
Because the set address data is
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