ee 47

ee 47 - EE 4770 Lecture Notes Generated from file...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon

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

View Full DocumentRight Arrow Icon

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

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: EE 4770 Lecture Notes Generated from file lsli15.dvi. This page was generated using an imperfect translator. Text may be poorly positioned and mathematics will be barely readable. Illustrations will not show at all. If possible, view the PostScript versions of these notes. 15-1 * * 15-1 Interrupts Interrupt: (verb) the interruption of a CPU's normal processing : : : : : :using a mechanism provided for this purpose. Interrupt: (noun) an event that causes an interrupt. An interrupt can be any of the following:- Interruption by an external_device________. In class, this is what is meant by interrupt.- Interruption by attempted illegal__ instruction or memory access. Also called exceptions.- Interruption by timer___ within computer.- "Interruption" by execution of a special_instruction________. Also called traps. (Used for system calls.) In this set, external-device interrupt will be covered. 15-1 EE 4770 Lecture Transparency. Formatted 10:29, 21 April 1997 from lsli15* *. 15-1 15-2 * * 15-2 External-Device Interrupts Hardware & Software Involved- External Event Possible events Temperature exceeding limit. Person pressing a button. Disk drive signaling that data is ready.- Sensor, Conditioning Circuit, Etc. Converts event to a logic level. This was covered earlier in the semester.- Computer Input, Called Interrupt Request (IRQ) Usually several IRQs available. A single IRQ can be shared.- Kernel Code Called Service Routine Attends to routine matters.- Kernel Code Called Handler Called by service routine. Attends to cause of interrupt. 15-2 EE 4770 Lecture Transparency. Formatted 10:29, 21 April 1997 from lsli15* *. 15-2 15-3 * * 15-3 Interrupt Steps, Overview Overview of Interrupt Activities- Event occurs. Detected by sensor.- An IRQ asserted by conditioning-circuit output.- When CPU allows interruption : : : : : :it finishes in-progress instructions : : : : : :prevents (masks) other interrupts : : : : : :and jumps to service routine.- Service routine : : : : : :saves context : : : : : :determines source of interrupt : : : : : :and calls handler for interrupt source.- Handler : : : : : :stops interrupt : : : : : :and carries out interrupt-specific activities.- After the handler returns : : : : : :the service routine restores registers : : : : : :and any interrupted task resumed. 15-3 EE 4770 Lecture Transparency. Formatted 10:29, 21 April 1997 from lsli15* *. 15-3 15-4 * * 15-4 Software Interrupts Exceptions These are caused by illegal instructions, operands, and memory ac- cesses....
View Full Document

This note was uploaded on 07/18/2011 for the course EE 4770 taught by Professor Staff during the Fall '99 term at LSU.

Page1 / 13

ee 47 - EE 4770 Lecture Notes Generated from file...

This preview shows document pages 1 - 4. Sign up to view the full document.

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