Interrupt acknowledge registers, End-of-interrupt registers – Motorola MVME2300 Series User Manual
Page 156
2-86
Computer Group Literature Center Web Site
Raven PCI Bridge ASIC
2
Interrupt Acknowledge Registers
On PowerPC-based systems, Interrupt Acknowledge is implemented as a
read request to a memory-mapped Interrupt Acknowledge register.
Reading the Interrupt Acknowledge register returns the interrupt vector
corresponding to the highest-priority pending interrupt. Reading this
register also has the following side effects.
❏
The associated bit in the Interrupt Pending register is cleared.
❏
Reading this register will update the In-Service register.
Reading this register without a pending interrupt will return a value of $FF
hexadecimal.
End-of-Interrupt Registers
EOI
End Of Interrupt. There is one EOI register per
processor. EOI code values other than 0 are currently
undefined. Data values written to this register are ignored;
zero is assumed. Writing to this register signals the end of
Offset
Processor 0 $200A0
Processor 1 $210A0
Bit
3
1
3
0
2
9
2
8
2
7
2
6
2
5
2
4
2
3
2
2
2
1
2
0
1
9
1
8
1
7
1
6
1
5
1
4
1
3
1
2
1
1
1
0 9 8 7 6 5 4 3 2 1 0
Name
VECTOR
Operation
R
R
R
R
Reset
$00
$00
$00
$FF
Offset
Processor 0 $200B0
Processor 1 $210B0
Bit
3
1
3
0
2
9
2
8
2
7
2
6
2
5
2
4
2
3
2
2
2
1
2
0
1
9
1
8
1
7
1
6
1
5
1
4
1
3
1
2
1
1
1
0 9 8 7 6 5 4 3 2 1 0
Name
EOI
Operation
R
R
R
R
W
Reset
$00
$00
$00
$0
$0