FUNCTION
AL DESCRIPTION
I N T E R R U P T I D E N T I F I C A T I O N
R E G I S T E R
+------+
D7 | FFE |--+
+------+ +-- FIFO enable
*
D6 | FFE |--+
+------+
D5 | 0 |
+------+
D4 | 0 |
+------+
D3 | IID2 |--+
+------+ |
D2 | IID1 | +-- Interrupt identification
+------+ |
D1 | IID0 |--+
+------+
D0 | IP |----- Interrupt pending
+------+
FFE - FIFO Enable:
*
When logic 1, indicates FIFO mode enabled.
IIDx - Interrupt Identification:
I n d i c a t e s h i g h e s t p r i o r i t y i n t e r r u p t p e n d i n g i f
a n y . S e e I P a n d f i g u r e 3 . N O T E : I I D 2 i s
a l w a y s a l o g i c 0 i n t h e 1 6 4 5 0 a n d i n t h e 1 6 5 5 0
character mode.
IP - Interrupt Pending:
W h e n l o g i c 0 , i n d i c a t e s t h a t a n i n t e r r u p t i s
p e n d i n g a n d t h e c o n t e n t s o f t h e i n t e r r u p t
i d e n t i f i c a t i o n r e g i s t e r m a y b e u s e d t o d e t e r m i n e
the interrupt source. See IIDx and figure 3.
* with optional 16550.
