NH82801DB S L8DE Intel, NH82801DB S L8DE Datasheet - Page 116

• Manufacturer Part Number: NH82801DB S L8DE
• Manufacturer: Intel

Specifications of NH82801DB S L8DE

• Lead Free Status / RoHS Status: Compliant

Functional Description
116
Table 5-20. EOI Message
EOI Message for Level Triggered Interrupts
EOI messages are used by local APICs to send an EOI cycle occurring for a level-triggered
interrupt to an I/O APIC. This message is needed so that the I/O APIC can differentiate between a
new interrupt on the interrupt line versus the same interrupt on the interrupt line. The target of the
EOI is given by the local APIC through the transmission of the priority vector (V7 through V0) of
the interrupt. Upon receiving this message, the I/O APIC resets the Remote IRR bit for that
interrupt. If the interrupt signal is still active after the IRR bit is reset, the I/O APIC will treat it as a
new interrupt.
Cycle
2–5
10
11
12
13
14
1
6
7
8
9
NOT(C1)
NOT(V7)
NOT(V5)
NOT(V3)
NOT(V1)
NOT(A1)
NOT(A)
ARBID
Bit 1
0
1
1
NOT(V6)
NOT(V4)
NOT(V2)
NOT(V0)
NOT(C0)
NOT(A1)
NOT(A)
Bit 0
0
1
1
1
EOI message
Arbitration ID
Interrupt vector bits V7 - V0 from redirection table
register
Check Sum from Cycles 6–9
Postamble
Status Cycle 0
Status Cycle 1
Idle
Intel
Comments
®
82801DB ICH4 Datasheet