NEC V30MZ interrupts

The NEC V30MZ provides six of the eight interrupts provided by the 80186.

Interrupts

INT 0 - Divide Error

This interrupt is emitted as the result of a DIV^IDIV or DIVU^DIV instruction.

INT 1 - Single Step/Break

This interrupt is emitted if the single step flag is set after executing an instruction. (The instruction which changed the single step flag is ignored.) The single step flag is cleared for the duration of the interrupt, allowing the user to store state and perform debug activities; it is then restored when returning from the interrupt, by restoring the original processor flags stored on the stack.

INT 2 - Non-Maskable interrupt (NMI)

This interrupt is emitted when the SoC requests a non-maskable interrupt. On the WonderSwan, the condtions for emitting an NMI are configured by the relevant I/O port.

INT 3 - Breakpoint

This interrupt is emitted by the INT 3^BRK instruction. Unlike other unconditional interrupt instructions, it is encoded with only one byte.

INT 4 - Overflow

This interrupt is emitted by the INTO^BRKV instruction, if the overflow flag is set while it is being executed.

INT 5 - Array Bounds

This interrupt is emitted only by the BOUND^CHKIND instruction.

Timing

TODO

Notes

• The following 80186 interrupts are not implemented:
  • INT 6 - Unused Opcode - the V30MZ treats most unimplemented instructions as NOPs.
  • INT 7 - ESC Opcode - the V30MZ, likewise, treats these instructions as NOPs.