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[Wheels-Of-Fire]

And Pt 2 is better. It is actualy useful for those of us who still dabble in assembly language.

[Ed P]

“Each vector is four bytes long and the 8088 can use 256 of them so Intel reserves the first 1K of memory for their use. It is also possible to call an interrupt in software with the INTn instruction where “n” is a number from 0 to 255 and DOS uses this to call BIOS routines.”

Thanks for the article, this little section reminds me of a time (early 80s) I was an IT troubleshooter. I got a call for help from a relatively backward country to look at a software maintenance contract. When I got there I found to my complete surprise that someone had managed to construct a six bay automated truck loading system (authorisation & billing) all built around an old IBM PC. The whole lot was programmed in compiled Borland Pascal and other than the accounting functions all driven in real-time using the interrupt system (both ways) and a  shed-load of PICS. The amazing thing was that it worked darned well!

As a post-script their contract was OK, they had all the software source code and full rights to it — their real problem would be where they could find someone who could take over its maintenance if and when the original programmers(two) went away to earn big bucks.

[Wheels-Of-Fire]

Thanks for the comment Ed. That system sounds like trouble waiting for the programer to leave ? interrupts are a good idea for a real time system though.

[Wheels-Of-Fire]

I said there was going to be a part 2 to my article on PC interrupts but its taken me longer to write than I thought. For the monent I am posting the first paragraph for review and comment.

I promice the rest of part 2 really does cover message signaled interupts and I will post it when its finished.

There is also now going to be a part 3 that covers how Windows handles interrupts.

[Author]

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