Table 33 - Interrupt Control Table
FIFO
INTERRUPT
MODE IDENTIFICATION
ONLY
REGISTER
INTERRUPT SET AND RESET FUNCTIONS
BIT
3
BIT
BIT
1
BIT PRIORITY
INTERRUPT
TYPE
INTERRUPT
SOURCE
INTERRUPT
RESET CONTROL
2
0
1
0
1
0
LEVEL
0
0
0
1
-
None
None
-
Highest
Receiver Line
Status
Overrun Error,
Parity Error,
Reading the Line
Status Register
Framing Error or
Break Interrupt
0
1
1
1
0
0
0
0
Second
Second
Received Data
Available
Receiver Data
Available
Read Receiver
Buffer or the FIFO
drops below the
trigger level.
Character
Timeout
Indication
No Characters
Have Been
Removed From
or Input to the
RCVR FIFO
Reading the
Receiver Buffer
Register
during the last 4
Char times and
there is at least 1
char in it during
this time
0
0
0
0
1
0
0
0
Third
Transmitter
Transmitter
Reading the IIR
Holding Register Holding Register Register (if Source
Empty
Empty
of Interrupt) or
Writing the
Transmitter
Holding Register
Fourth
MODEM Status
Clear to Send or Reading the
Data Set Ready MODEM Status
or Ring Indicator Register
or Data Carrier
Detect
72
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