Exceptions - Fujitsu MB90335 Series Hardware Manual

CHAPTER 3 INTERRUPT

3.9 Exceptions

3.9 Exceptions
2
The F MC-16LX performs exception processing when the following event occurs.
■ Execution of an Undefined Instruction
Exception processing is fundamentally the same as interrupt processing. When an exception is detected
between instructions, exception processing is performed separately from ordinary processing. In general,
exception processing is performed as a result of an unexpected operation. Fujitsu Microelectronics
recommends using exception processing only for debugging or for activating emergency recovery software.
■ Exception due to Execution of an Undefined Instruction
2
The F MC-16LX handles all codes that are not defined in the instruction map as undefined instructions.
When an undefined instruction is executed, processing equivalent to the INT 10 software interrupt
instruction is performed. Specifically, the AL, AH, DPR, DTB, ADB, PCB, PC, and PS values are saved
into the system stack, and processing branches to the routine indicated by the interrupt number 10 vector. In
the undefined instruction is stored. Processing can be restored by the RETI instruction, but is of no use,
however, because the same exception occurs again.
102 FUJITSU MICROELECTRONICS LIMITED
MB90335 Series
CM44-10137-6E