HD6432621 Hitachi, HD6432621 Datasheet - Page 583

• Manufacturer Part Number: HD6432621
• Description: (HD64F262x Series) 16-Bit Microcomputer
• Manufacturer: Hitachi

Bit 1—Unread Interrupt Flag (IRR9): Status flag indicating that a receive message has been
overwritten while still unread.
Bit 1: IRR9
0
1
Bit 0—Mailbox Empty Interrupt Flag (IRR8): Status flag indicating that the next transmit
message can be stored in the mailbox.
Bit 0: IRR8
0
1
Description
[Clearing condition]
Clearing of all bits in UMSR (unread message status register) (Initial value)
Unread message overwrite
[Setting condition]
When UMSR (unread message status register) is set
Description
[Clearing condition]
Writing 1
Transmit message has been transmitted or aborted, and new message can
be stored
[Setting condition]
When TXPR (transmit wait register) is cleared by completion of transmission
or completion of transmission abort
(Initial value)
539