MESSAGE
| DATE | 2015-02-04 |
| FROM | Ruben Safir
|
| SUBJECT | Subject: [LIU Comp Sci] (fwd) Re: Operating System Design
|
From owner-learn-outgoing-at-mrbrklyn.com Wed Feb 4 13:23:13 2015
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From: Ruben Safir
To: learn-at-nylxs.com
Subject: [LIU Comp Sci] (fwd) Re: Operating System Design
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From: Lew Pitcher
Subject: Re: Operating System Design
Newsgroups: comp.os.linux.hardware
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On Thursday January 29 2015 17:11, in comp.os.linux.hardware, "ruben safir"
wrote:
> I'm wondering if anyone has a background in operating system design.
> I'm taking a class is OS's and the text is
>
> OPERATING
> SYSTEM
> CONCEPTS
> ABRAHAM SILBERSCHATZ
Don't know the book, so my remarks will have to be somewhat generic.
> 9th edition, and it says something that is puzzling me
>
>
>
> "Interrupts are an important part of a computer architecture. Each
> computer design has its own interrupt mechanism, but several functions
> are common. The interrupt must transfer control to the appropriate
> interrupt service routine. The straightforward method for handling this
> transfer would be to invoke a generic routine to examine the interrupt
> information. The routine, in turn, would call the interrupt-specific
> handler. However, interrupts must be handled quickly"
>
> " Since only a predefined number of interrupts is possible, a table of
> pointers to interrupt routines can be used instead*** to provide the
> necessary speed. The interrupt routine is called indirectly through the
> table, with no intermediate routine needed. Generally, the table of
> pointers is stored in low memory (the first hundred or so locations).
> These locations hold the addresses of the interrupt service routines for
> the various devices. This array, or interrupt vector, of addresses is
> then indexed by a unique device number, given with the interrupt
> request, to provide the address of the interrupt service routine for
> the interrupting device. Operating systems as different as Windows and
> UNIX dispatch interrupts in this manner."
>
>
> *** Instead of what?
Certain hardware interrupts cause an execution branch to a specific
location. Typically, the hardware will provide some identifying information
available through an I/O call, and the logic branched to must then poll
each eligible device for that information. Once the device has been
identified and the information extracted, the logic can then process the
interrupt condition.
Certain software interrupts also can cause an execution branch to a specific
location. Typically, the software interrupt code will provide some
identifying information available through inspection of the memory pointed
to by interrupt program-counter. Once this information has been extracted,
the logic can then process the interrupt condition.
Both of these types of interrupt expect to execute logic at a specific
location, hardwired into the interrupt mechanism.
[snip]
HTH
--
Lew Pitcher
"In Skills, We Trust"
PGP public key available upon request
-- end of forwarded message --
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