ch12-8259A_PIC

ch12-8259A_PIC - Interrupt Priority Management: 8259A EE...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Interrupt Priority Management: 8259A EE 3750 2 8259A programmable interrupt controller 8-level priority controller expandable to 64 levels by cascading 8259As Actions: accepts interrupt requests from I/O devices determines which request has highest priority determines whether this incoming request has higher priority than the ones currently being serviced issues interrupt request to processor sends interrupt type to processor in response to interrupt acknowledgment
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
figure from Intel 3 Blocks interrupt request register (IRR) stores all interrupt levels requesting service priority resolver selects highest priority request in IRR, determines whether higher priority than anything in ISR in-service register (ISR) stores interrupt levels that are being serviced not necessarily all that are currently being serviced interrupt mask register (IMR) 4 Interrupt sequence 1. One or more of the INTERRUPT REQUEST lines (IR7-0) are raised
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 4

ch12-8259A_PIC - Interrupt Priority Management: 8259A EE...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online