Hitachi H8S/2646 Hardware Manual page 921

Bit 7
—
Initial value 1
Read/Write —
Bus Operation Interrupt Mask
0
1
6 5
— —
1 1
— —
Unread Interrupt Mask
0 Unread message overwrite interrupt request to CPU by IRR9 enabled
1 Unread message overwrite interrupt request to CPU by IRR9 disabled
Bus operation interrupt request to CPU by IRR12 enabled
Bus operation interrupt request to CPU by IRR12 disabled
4 3
IMR12 —
1 1
R/W —
Mailbox Empty Interrupt Mask
0 Mailbox empty interrupt request to CPU by IRR8 enabled
1 Mailbox empty interrupt request to CPU by IRR8 disabled
2 1 0
— IMR9 IMR8
1 1 1
— R/W R/W
889