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N OTES ON USE
4.1.3 Distinction of interrupt request bit
When executing the BBC or BBS instruction to an interrupt request (request distinguish) bit
of an interrupt request register (interrupt request distinguish register)
immediately after this
bit is set to “0” by using a data transfer instruction
✽
, execute one or more instructions before
executing the BBC or BBS instruction.
Fig. 4.1.2 Distinction sequence of interrupt request bit
✽
Data transfer instruction : LDM, LDA, STA, STX, STY
●
Reason
If the BBC or BBS instruction is executed immediately after an interrupt request (request
distinguish) bit of an interrupt request register (interrupt request distinguish register) is
cleared to “0,” the value of the interrupt request (request distinguish) bit before being cleared
to “0” is read.
Clear an interrupt request (request distinguish) bit to “0”
(no interrupt request issued)
NOP instruction (one or more instructions)
Execute the BBC or BBS instruction
