Distinction Of Interrupt Request Bit - Mitsubishi M16C/60 Series Software Manual

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.
Clear an interrupt request (request distinguish) bit to "0"
(no interrupt request issued)
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.
NOP instruction (one or more instructions)
Execute the BBC or BBS instruction
N OTES ON USE
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